WCOX B Water-Cooled Packaged Chillers with Helical Rotary Compressors

Transcription

1 WCOX056-07B Water-Cooled Packaged Chillers with Helical Rotary Compressors Installation, Operation, and Maintenance Instructions TABLE OF CONTENTS PAGE. GENERAL INFORMATION...2. Receiving and Inspection Rigging and Moving Dimensional Data Application Precautions INSTALLATION Foundation Vibration Isolation Water Piping Connections Electrical Wiring Controls Request for Start-Up Representative OPERATION System Water Flow Rate Seasonal Shut-Down Procedure Seasonal Start-Up Procedure Safety Relief Valves Refrigeration Cycle Oil System Hydraulic Capacity Control System Freeze Protection ELECTRICAL Hz Electrical Data Wiring Diagram Typical Operation Microcomputer Controller Control & Safety Functions MAINTENANCE General Periodic Inspection Monthly Inspection Water Side Cleaning of Vessels Electrical Malfunction Charging Troubleshooting Sample Log Sheet WCOX SERVICE PARTS LIST Form 686

2 INTRODUCTION This equipment is a factory built and tested packaged chiller designed for the purpose of cooling water or other noncorrosive liquid. The liquid to be cooled is to be circulated through the tubes of a refrigerant evaporator (hereafter referred to as a cooler) where the temperature is reduced to the desired level. The heat absorbed by the refrigerant in the cooler is rejected via the condenser where it raises the temperature of another liquid stream (usually water) being circulated through the tubes. This heat is usually rejected via a cooling tower or closed circuit cooler. To assure satisfactory operation and to avoid damage to the unit, the installation should be made by a qualified refrigeration mechanic. It is assumed that the reader of this manual and those who install, operate and maintain this equipment have a basic understanding of the principles of air conditioning, refrigeration and electrical controls. These instructions are general in nature and are for standard catalog units. Non-standard units may vary in some respects from these instructions. Your Dunham-Bush packaged chiller has been manufactured under a careful quality control system. It has been performance tested at the factory at specified field operating conditions as a final verification of reliability. If it is installed, operated and maintained with care and attention to these instructions, it will give many years of satisfactory service.

3 . GENERAL INFORMATION. RECEIVING AND INSPECTION The unit should be inspected immediately, in the presence of the carrier s representative, for any evidence of damage during shipping. Any damage should be noted on the carrier s delivery receipt before it is signed. A damage claim should then be filed by the purchaser against the delivering carrier as all shipments are made at the purchaser s risk. The receiving inspection instructions. (Form 924), sent with the installation instructions, should also be filled out at this time and forwarded to the Dunham-Bush, Inc., North American Service Department, Harrisonburg, VA RIGGING AND MOVING Each unit has been carefully tested and inspected at the factory where every precaution was taken to ensure that it reaches its destination in perfect condition. It is very important that the installers, movers, and riggers use the same care in handling the unit. A forklift may only be used to move the unit when equipped with the optional skid. The unit can be lifted by a crane from lifting holes provided on the vessel tubesheets. For proper rigging, see Fig.. FIGURE RIGGING INSTRUCTIONS LIFT FROM THESE LOCATIONS ONLY! CONDENSER COOLER NOTES: DO NOT SKID UNIT UNLESS UNIT IS EQUIPPED WITH FACTORY INSTALLED SKID OPTION. 2

4 .3 DIMENSIONAL DATA Dimensional outline drawings of the packages are shown in Figure 4. Note especially the space and clearance requirements necessary for servicing the unit..4 APPLICATION PRECAUTIONS The following instructions are intended to help assure proper and successful application of your water chilling machines..4. Chilled Water Flow The Dunham-Bush WCOX Packaged Water Chiller is designed for a constant chilled water flow rate, even when the cooling load is varying. The machine will generally perform satisfactorily with steady flow rates deviating from design by as much as +0% / -50%. However, varying water flow rates can cause control instability which will result in undesirable system effects, particularly poor control of leaving chilled water temperature. If two-way valves are used to control flow through cooling coils, some means such as an automatic modulating valve should be provided in the system to maintain steady flow through the cooler. If the chilled water system is arranged for the dual purpose of cooling and heating, the cooler must incorporate valves to prevent the flow of hot water through it. This can be done with either manual or automatic shutoff valves, but the method of control must be such that water temperature entering the cooler never exceeds 90 F..4.2 Water Cooled Condensers The water cooled condenser is also designed for constant water flow rate, and should be supplied with the design GPM ±0%. The condenser must be protected from rapid changes in temperature as well. Fluctuating flow rate or temperature will cause unstable control of the machine, resulting in poor control of leaving chilled water temperature. If a cooling tower is used to reject heat from the condensing water loop, it must be controlled to provide an entering condensing water temperature which does not change rapidly and does not go below 60 F. One or more of the following methods may be used to control the tower:.4.2. A modulating three-way valve which by-passes tower sprays at low load and low ambient temperature Tower fan staging in response to a thermostat in the tower sump. Fan thermostat should have a differential of at least 20 F to avoid short-cycling A modulating three-way valve which by-passes the cooling tower to blend warm leaving condenser water with cold tower water..4.3 Condensing Water Treatment Condensing water tends to leave silt, algae and mineral deposits in the condenser tubes. This fouling gradually decreases unit efficiency. For this reason, a program of water treatment should be employed. Also, at regular intervals depending on water quality, the unit should be shut down, condenser heads removed and tubes cleaned. See Section INSTALLATION 2. FOUNDATION A flat, level concrete foundation or floor capable of supporting the weight of the unit must be provided. Weights are given in Table. The unit must be levelled to within /6" per foot for proper operation 2.2 VIBRATION ISOLATION Where structure-borne vibration may be of concern, it is recommended that the unit be mounted on vibration isolators. Spring isolators are available for this unit as optional equipment. If spring isolators are installed, it is also necessary to provide isolation in condenser water and chilled water pipes by means of flexible connectors and in main power supply conduit through use of flexible conduit. Isolation of piping and electrical conduit is desirable in any event, to avoid noise transmission. 3

5 Table PHYSICAL SPECIFICATIONS WCOX Unit Model WCOX056 WCOX066 WCOX080 WCOX089 WCOX07 Compressor Hz RPM Shipping Wt. (lb) - Std. Vessels 23,620 26,94 3,764 34,962 40,975 Operating Wt. (lb) - Std. Vessels 25,670 29,394 34,754 38,282 44,965 Approx. R-22 Charge, lbs Standard Vessel Nomenclature B5 C5 D5 E5 G5 Standard Cooler Model EF3063 EF3463 EF3763 EF3963 EF4363 Design press. Water Side (PSIG) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code) Design Press. R-22 Side (PSIG) Min. GPM/PD (Ft., Pass) 852/0.9 02/ / / /0.9 Min. GPM/PD (Ft., 2 Pass) 426/.7 50/.7 67/.7 683/.7 823/.7 Min. GPM/PD (Ft., 3 Pass) 286/ / / /2.7 56/2.7 Max. GPM/PD (Ft., Pass) 4260/ / / / /8. Max. GPM/PD (Ft., 2 Pass) 230/ / / / /32.3 Max. GPM/PD (Ft., 3 Pass) 303/ / / / /45. Standard Condenser Model CD3063 CD3463 CD3763 CD3963 CD4363 Design Press. Water Side (PSIG) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code) Design Press. R-22 Side (PSIG) Min. GPM/PD (Ft., Pass) 884/. 064/. 278/. 46/.0 687/. Min. GPM/PD (Ft., 2 Pass) 442/ / / / /2.0 Max. GPM/PD (Ft., Pass) 4420/ /2. 639/ / /2.0 Max. GPM/PD (Ft., 2 Pass) 220/ / / / /37.8 4

6 2.3 WATER PIPING CONNECTIONS After the unit has been levelled and isolators (if any) installed and adjusted, connect cooler and condenser water piping. Piping must be properly supported to avoid stress on unit water connections. Install air vent valves in all high connections on cooler and condenser heads. Install drain valves in similar low points to facilitate gravity draining of the system. It is important that water systems be cleaned before start-up to avoid collecting debris in cooler and condenser. The best way to do this is to install wye strainers in both systems upstream of the unit. After filling systems with water, bleed trapped air from the various vent valves. Check for proper flow rates by measuring water pressure drop across heat exchangers and reading GPM from charts, Figure 2. Compare measured GPM's with values specified on purchase order. In connecting power wiring to the unit, the following precautions should be taken: 2.4 ELECTRICAL WIRING All field wiring is to be in accordance with the National Electric Code and must comply with state and local codes. Check unit wiring for damage and all terminal connections for tightness. Unit terminal blocks are to be connected with copper conductors only, sized per ampacity listed on unit data plate. Connections to unit should match the unit nameplate in volts, phase, and Hertz. Voltage must not vary beyond ±0% of nameplate value and voltage imbalance between phases must not exceed 2% at any time during operation of the unit. 2.5 CONTROLS 2.5. Connections Phase sequence to connections L L 2 L 3 shall be in that order. Check with Amprobe phase sequence adapter PSA- or equivalent. For minimum circuit ampacity and fuse size, consult unit nameplate. All units have running overload protection as standard. When the transformer option is not supplied, a direct connected 5 VAC ±0% circuit must be supplied. The over current protection for the circuit must be 30A. Use #0AWG copper conductors. Wire to terminal block TB. Use terminal #2 for connection of the ground supply conductor. Controls which are to be field installed should be connected in accordance with the appropriate wiring diagram accompanying the unit. The following connections should be made where applicable: Install a chilled water flow switch (paddle type recommended) in straight length of chilled water piping to avoid turbulence. Connect in same electrical circuit as Connect a set of normally open auxiliary contacts from chilled water pump contactor into unit controls as shown on unit wiring diagram Settings For control of condensing water pumps, connect contacts supplied in unit in series with condensing water pump starter coil. All controls are factory set, however operating control settings are not always applicable under all operating conditions. For recommended control settings, se wiring diagram accompanying unit. Safety controls must be set to factory recommendations. 2.6 REQUEST FOR START-UP REPRESENTATIVE After the installation has been completed and checked, Form 980 must be filled out and sent to North American Service Department of Dunham-Bush, Inc. for authorized start-up representative to perform the initial start-up of the Dunham-Bush packaged chiller. The purchaser will have competent service and operating personnel in attendance to assist in the work involved, and also to be trained in the service and maintenance of this unit. (During the warranty period, the manufacturer is responsible for parts only upon proof of defective workmanship or manufacture). Following receipt of the signed Form 980, a representative will be sent to the customer. He will inspect the installation to determine whether it meets specified customer personnel in its operation and maintenance for the length of time specified in the purchase contract. NOTE: Sump oil heaters should be energized for a minimum of 24 hours and the oil sump temperature must be at a minimum of 00 F (38 C) prior to arrival of start-up representative. This will ensure that the oil is warm enough to vaporize any dissolved refrigerant and that the oil is within the normal operating temperature range. WARNING The compressor(s) should be started initially ONLY under the direct supervision of an Authorized Dunham-Bush, Inc., Start-Up Representative. 5

7 The quantity of chilled water being circulated can be measured quite accurately (±5%) by determining the water pressure drop through the cooler and reading GPM from cooler pressure drop curve, Figure 2. Connect reliable pressure gauges to valves installed in cooler entering and leaving water vent connections 3. OPERATION 3. SYSTEM WATER FLOW RATE 3.2 SEASONAL SHUT-DOWN PROCEDURE 3.2. If the unit is to be shut down for a prolonged period (a month or more), the power supply to the unit may be de-energized to conserve energy The cooling tower may be drained to avoid freezing. If the unit is located in an area where the ambient temperature constantly remains above freezing, the condenser need not be drained. It is better to leave the condenser and cooler filled with water during shutdown period. If the unit is located where ambient temperature will be below freezing, drain all water thoroughly, removing all vent and drain SEASONAL START-UP PROCEDURE and read pressure difference with chilled water pump in operation. Condenser water flow rate can be measured in the same way. An alternate method of determining GPM is to measure pressure difference from pump inlet to outlet and read GPM from pump curve. plugs from both heads of each vessel, and blow out tubes with compressed air. NOTE: Simply draining is not sufficient. Stagnant water may cause serious corrosion It is recommended that an oil sample be taken from the compressor and submitted for laboratory analysis. Dunham-Bush offers this service in its Oil Kare Program. This analysis should be done at the beginning and end of each operating season, or every six months if the unit is used year round. When the unit is to be started up after being shut down for a prolonged period: 3.3. Check unit for evidence of rust or corrosion. Clean surfaces and repaint as necessary. Repair insulation if necessary Energize power supply to unit. Unit must be energized for 24 hours in order to warm up oil sump before starting. Control circuit power switch should be off during this period to prevent compressor operation. Clean water side heat transfer surface of condenser and cooler by removing heads and brushing tubes Check water circuits to see that cooling tower is ready for operation, and both circuits are filled. Start pumps and check for flow in both cooler and condenser Turn control circuit power switch on, turn compressor switch on, and press reset on computer keyboard. Compressor should start after start-up clock times out and leaving water temperature should be automatically controlled. Check refrigerant charge and check for normal suction and discharge pressures Have a trained service mechanic check the function of all control setpoints. Check signal lights for proper operation Take oil sample from the sump and submit it for laboratory analysis SAFETY RELIEF VALVES Each pressure vessel is protected by a safety relief valve as required by ASME Code. The condenser has a dual manifold. One valve in this manifold is active, the other standby. If the active valve starts to 3.5 REFRIGERATION CYCLE leak, simply screw the manifold valve to the opposite extreme, which will activate the standby valve. Local codes may require that all safety relief valves be piped to the outdoors. Never install a hand valve in a safety relief vent line. Following is the normal sequence of operation for a unit installed in a typical air conditioning system and served by a cooling tower. Refer to Figure 4, the piping schematic for a WCOX unit. The large screw compressor discharges warm, high pressure gas through a discharge service valve () into the condenser, where the oil is separated. The gas is condensed outside tubes, rejecting heat to cooling tower water flowing inside the tubes. The liquid refrigerant drains to the bottom of the condenser and exits into the liquid line. The refrigerant flows by a charging valve (2), past a condenser drain sight glass (3), and through a modulating ball valve (4) which is 6 driven by a modutrol motor (5). The motor adjusts the valve to maintain an appropriate level in the cooler, determined by a liquid level float switch (6), and measurement of compressor discharge superheat. From the modulating valve, liquid refrigerant flows into the flooded cooler, where it boils, cooling the water flowing inside the cooler tubes. Vapor from the boiling refrigerant flows up the suction pipe through a suction check valve (7) into the compressor where it is compressed and starts the cycle again.

8 Figure 2 Water Pressure Drop Data CONDENSER Two Pass PRESSURE DROP, FEET OF WATER One Pass FLOW (GPM) FLOODED EVAPORATORS Three Pass PRESSURE DROP, FEET OF WATER Two Pass One Pass FLOW (GPM) 7

9 Figure 3 Dimensional Data 8

10 Figure 4 Typical Piping Schematic CONDENSER COOLER REFRIGERATION CIRCUIT PUMPED OIL CIRCUIT OIL RETURN CIRCUIT UNLOADER CIRCUIT 9

11 3.6 OIL SYSTEM 3.6. Oil Supply System The compressor's oil is supplied from a sump in the condenser by an external pump. This oil is used to actuate the slide valve and lubricate the bearings, rotors, and seals in the compressor. Figure 4 illustrates oil from the condenser sump feeds past an oil charging port (8), through an isolation valve (9), a suction strainer (0), and the oil pump (). From there it passes through a filter (2), another isolation valve (9), and into the compressor's main oil port. Seal oil leaves the injection manifold to be cooled in the seal oil cooler (6) in the condenser. A check valve (4) prevents backflow. A bypass valve (5) should be adjusted to keep oil returning to the compressor below 20 F at all times. Pressurized oil is also fed from another port on the compressor to the main oil injection supply for the rotors through a main oil injection adjusting valve (3) which is usually fully open, and must be open at least one full turn during operation to lubricate the rotors. Electric resistance heaters are located in the oil sump in the condenser vessel and serve to vaporize excess refrigerant that would otherwise dilute the oil during shutdown by heating the oil to a suitable temperature. The heaters must be energized a minimum of 24 hours prior to start up of the unit. Two oil sump sight glasses are provided. During normal operation or shutdown, the bottom glass should indicate a partial oil level. The top glass should always be empty. The oil separator discharges a very small amount of oil mist along with refrigerant. This oil is carried into the cooler. As shown in Figure 4, oil-rich refrigerant is returned from the cooler through taps in the cooler shell through an oil return valve (9), filter drier (20), into a jet pump (8) installed on Oil Return System the suction line which received high pressure gas from the discharge line through a hot gas valve (7), which should be fully open. This forces the oil-rich mixture from the cooler into the suction line of the compressor. A sight glass (2) can be used to observe oil return rate. 3.7 HYDRAULIC CAPACITY CONTROL SYSTEM (SEE FIGURE 4) The compressor has a hydraulic control system to supply the proper force necessary to actuate the capacity control slide valve, thereby regulating compressor loading. It is controlled by the NC25-4 microcomputer, which provides signals to the load solenoid valve (25) and unload solenoid valve (22) to provide pressure to move the slide valve. Angle valves (3, 23, and 24) provide access to the solenoid valves, as well as factory adjustment of control rates. 3.8 FREEZE PREVENTION If water (or brine) is allowed to freeze within the tubes and heads of the cooler or condenser, severe damage will result; split and leaking tubes and cracked and leaking heads. Since this damage can be extremely costly and is not covered by warranty, it is important to be mindful of freeze prevention. Three cases deserve particular attention: If the unit is to stand idle at ambient temperatures below 32 F, the water should be drained from cooler and condenser. A head should be removed from each vessel and the tubes blown dry with compressed air. Freezing of water in cooler tubes is a possibility if chilled water flow stops and if the low suction pressure cutout (normally set for 58 psig, or 32 F saturation) and the low water temp cutout both fail. If the chilled water flow switch and pump interlock are properly applied (See and In transferring refrigerant within the unit, or releasing refrigerant from the unit for maintenance purposes, it is possible to freeze cooler or condenser tubes. Remember that whenever the pressure in a vessel is reduced below 3.8. Standby at Low Ambient Temperatures In Operation During Maintenance 0 Gravity draining the vessel through drains in heads may not be sufficient. If cooler or condenser are served with a glycol solution, make sure the freeze temperature of the solution is lower than expected minimum ambient temperature ) the unit has four protective devices which must all fail to produce freezing of the cooler in operation. While this is unlikely, it is important to see that all these devices are functional and properly calibrated. 58 psig, if water is not flowing, it is possible to freeze tubes. For this reason, it is a good precaution to have water flowing in both vessels whenever transferring refrigerant.

12 4. ELECTRICAL 4. ELECTRICAL DATA Compressor Motor Oil Pump Data Circ # Circ #2 WCOX Line Voltage `460V' Motor Size Volts HZ RLA LRA HP FLA Volts/PH/HZ MCA MFS MCA MFS Designation () (2) (4) (4) (5) (5) (6) (2) (22) J /3/ J /3/ J /3/ J /3/ J /3/ K /3/ K /3/ K /3/ K /3/ K /3/ L /3/ L /3/ L /3/ L /3/ L /3/ M /3/ M /3/ M /3/ M /3/ M /3/ N /3/ N /3/ N /3/ N /3/ N /3/ P /3/ P /3/ P /3/ P /3/ P /3/ Q /3/ Q /3/ Q /3/ Q /3/ Q /3/ R /3/ R /3/ R /3/ R /3/ R /3/ S /3/ S /3/ S /3/ S /3/ S /3/ T /3/ T /3/ T /3/ T /3/ T /3/ U /3/ U /3/ U /3/ U /3/ U /3/ V /3/ V /3/ V /3/ V /3/ V /3/

13 Figure 6 is a typical wiring diagram for a WCOX This may not be an accurate representation of your unit. It is best to use the wiring diagram 4.2 WIRING DIAGRAM 4.3 TYPICAL OPERATION mounted in the package control panel. A copy of that diagram is furnished with the unit owner's manual. In order to start a unit, the following conditions must be met: - chilled water pump running - chilled water flow switch made - customer control contact (optional) closed - control switch and compressor switch on - circuit breakers on - all safety conditions satisfied - reset pressed on microcomputer keypad - the compressor has not started within the last 20 minutes - leaving chilled water temperature 2 F or more above setpoint - oil sump temperature is greater than 70 F. The microcomputer starts the oil pump by energizing 4CP. If capacity indicator is below 8% and a minimum of 27 psid oil pressure is established, 5 seconds later the microcomputer signals 2CR which starts the compressor motor. Oil pressure and standby discharge pressure are then monitored to insure that a differential of at least 27 psid is maintained for 5 seconds. (The capacity indicator must also unload to less than 8%). The microcomputer then signals 2CR, which starts the compressor motor. When the compressor starts, the microcomputer monitors leaving water temperature, ramp schedule, and load limiting to control load and unload solenoids. The refrigerant level sensor and discharge temperature are used to control the refrigerant modulating motor (See 4.5.9). When minimum compressor capacity exceeds system load and water temperature falls below setpoint, the compressor and oil pump shut down. 4.4 MICROCOMPUTER CONTROLLER This unit is controlled by a microcomputer control system. The system is composed of four microcomputer boards, a display board and analog and digital sensors. The following sections describe the system and how to operate it. The display board has a 20-key keypad and a 2 x 40 LCD display. The keypad and display can be used to determine the status of the compressor, oil pump, and refrigeration system. Various setpoints can also be displayed and altered. The status of the machine can also be monitored by a computer terminal either locally or remotely by a modem. The terminal must be able to handle RS232 communications. For more information, order Form # TO DISPLAY DATA FROM THE MENU. Press the MENU key. 2. Use the up or down arrow keys to select the type of information desired. The main menu items are: DATE & TIME SET CONTROL POINTS ANALOG SENSORS DIGITAL SENSORS SETPOINTS A & B ALARMS AUTHORIZATION 3. Press the ENTER key. 4. Use the up or down arrow keys to select the desired data. For control points, additional data can be viewed with the right and left arrow keys. NOTE: When displaying analog sensors, the PAGE MODE key can be pressed to display two new analog inputs after each arrow key is pressed. Press PAGE MODE again to return to displaying one new analog in put TO RESET ALL CONTROL POINTS TO COMPUTER CONTROL. Press the RESET key. The display will show RESET ALL CPs to COM MODE? N Y 2. Press the right arrow key to select Y. 3. Press the ENTER key. The reset will not be accepted if a lockout control point is active. Resolve the problem and reset again. 2

14 Figure 6 Typical Wiring Diagraml A

15 B

16 4.4.3 TO DISPLAY ALARMS. Press the MENU key. 2. Use the up or down arrow to select ALARMS. 3. Press ENTER. 4. The day, time, and alarm code is displayed. Alarm is the most recent alarm. 5. Press the down arrow to view previous alarms. 6. To view the name of the alarm, display the digital input that corresponds to the alarm number. If the digital input name is SPARE, then display the control point that corresponds to the alarm number. EX: If alarm code 29 has occurred then display digital input 29 or control point 29 to determine the failure TO BECOME AUTHORIZED. Select AUTHORIZATION on the main memo. Press ENTER. 2. If the current status shown is VIEW, press the authorization code (64) on the number keys. 3. Press ENTER. the current status will change to PRG (program) if accepted TO ALTER SETPOINT DATA. You must be authorized and in the PROG mode. See section Select SETPOINTS A & B on the main menu. Press ENTER. 3. Use the up or down arrow keys to select the setpoint to be changed. Press ENTER. A cursor will flash over the setpoint A value. 4. a) If you want to change setpoint A, press in the desired new value and press ENTER. if the new value is within limits, it will be stored in memory. The cursor will then move to setpoint B. b) If you do not want to change setpoint A, press ENTER. 5. Repeat 5.4 for Setpoint B TO CALIBRATE TEMPERATURE AND PRESSURE SENSORS. You must be authorized and in the PROG mode. See Section Display the analog sensor to be calibrated on the top line of the display. 3. Press ENTER to show ZERO CALIBRATION value. 4. Use an accurate gauge to measure the analog value when it is stable and near design conditions. 5. Determine the revised zero calibration required as follows: Meter Reading - AI Display + Zero Calibration = New Zero Calibration. The new zero calibration must be rounded to the nearest whole number. 6. Press ENTER to place the cursor on the zero calibration value. 7. Enter the new value from 6.5. Negative values are entered by pressing LOWER FUNCTION +/- before the number. 8. Press ENTER to store the revised zero calibration. For example, if a suction pressure gauge shows 58 psig and the computer displays 60.3 psig with a zero calibration of -, then new calibration would be (-) = -3.3 (-3). So the zero calibration should be changed to TO SET DATE AND TIME. You must be authorized. See Section Select DATE & TIME SET on the main menu. Press ENTER to display current date and time. 3. Press ENTER key to move cursor to each date/time item. 4. As each item flashes, use the number keys to enter revised data if necessary. 5. Press ENTER to continue. The last ENTER will store the new date and time. WARNING: Setting the clock will cause a system reset. The entire unit will shut down and start over again. If the change was started inadvertently, press MENU key before completing the change TO DISPLAY DATA WITHOUT ACCESSING MENU. Press LOWER FUNCTION. 2. Press function desired (blue sub-script) 3. Press item number to be displayed. 4. Press ENTER. EX: To display analog input #5, press LOWER FUNCTION< ANALOG INPUT, 5, ENTER 5

17 Figure 7 Instruction Label 6

18 . See Section TO REVISE SCHEDULES 4.5 CONTROL AND SAFETY FUNCTIONS 4.5. Chilled Water Pump Interlock And Flow Switch (CWP AND CWFS) These are field installed switches, both of which are used to ensure chilled water flow before the unit is allowed to start. Failure of either one during operation will cause the compressor and oil pump to shutdown. A water flow alarm will be generated and RESET must be pressed to clear the alarm. NOTE: The flow switch or pump interlock cannot be used for normal control of the unit. (See 4.5.2) Customer Control Interlock Control contacts from an external controller can be used to enable or disable operation of the unit. The wiring diagram specifies the terminals to which the contacts must be wirted. To enable the unit, the contacts must be closed. To disable the unit, the contacts must be opened Anti-Recycle Timer (Microcomputer) The compressor motor requires an anti-recycle time delay which prevents restart for 20 minutes after a start. The purpose of this feature is to avoid frequent starts which tend to elevate the motor winding temperature and impose undue wear on contactors. The microcomputer will not restart the compressor motor until the 20 minutes have elapsed. COFF is displayed when the compressor control point (CP) is addressed, and when other conditions for compressor start are satisfied. See Section Load Control (Microcomputer) The microcomputer controls the leaving water temperature within a narrow deadband by pulsing load and/or unload solenoids on the compressor. The load and unload solenoids position the slide valve within the compressor to control its capacity. The microcomputer determines a desired level of loading and varies pulse duration depending on difference between load target and actual load. The load target is varied based on rate of approach to desired temperature preventing significant temperature oscillations. The current limit function (see Section 4.5.7) overrides the temperature control. The status of the compressor can be observed by displaying the compressor control point (/CONTROL POINT). One of the following messages will be displayed: COMP LOAD Automatic load COMP HOLD Automatic hold COMP UNLD Automatic unload COMP OFF Off on temperature or customer control COMP COFF Off on timer (C lock off) COMP LOFF Manual off or safety shutdown Unload Start (Microcomputer) On packages with wye-delta starters, a refrigerant bypass is required at start. The microcomputer turns the bypass solenoid on when the oil pump starts and turns it off 30 second after the compressor starts Ramp Control (Microcomputer) Another feature of the microcomputer is ramp control, which is the ability to vary load time of the machine from start. Often when the machine is started, the water in the chilled water circuit is warm, and the unit will go to full load quickly. With ramp control, the user can program the computer so that it loads at a predetermined rate. This is a valuable tool, since it can help reduce power consumption and demand charges. Two variables are used to define the ramp profile: Ramp rate and start point. Ramp rate defines the length of time the unit takes to load from start point to full load. Start point is the percent of full load at which the ramp begins. The ramp rate A setpoint can be set anywhere from 0. to 0.4, smaller values producing slower loading rates. The ramp start B setpoint can be set anywhere between 0 and 50%. The compressor will load quickly to this value and then follow the ramp slope from there. See Table 4 for ramp rates at various settings. 7

19 TABLE 4 Ramp Rates for Several Setpoints (in Minutes) Ramp Start Point Setpoint Rate Setpoint 0% 20% 50% Current Limiting (Microcomputer) A maximum desired current is specified by amp limit B setpoint for the compressor. Above the B setpoint, the compressor will not load. If the amps rise above the A setpoint, the computer will give an unload command to the compressor until the current drops below the A setpoint. The amp value in the A setpoint should be 0% of RLA higher than the B setpoint. When hot gas bypass has been supplied with the package, an output from the computer controls the solenoid. The solenoid is turned on if the target percent capacity of the compressor drops Hot Gas Bypass (Factory-installed option) Refrigerant Management below the hot gas bypass B setpoint. If the target percent capacity then climbs above the hot gas bypass A setpoint, the solenoid is turned off. Typical setpoints are 25% for the B setpoint and 60% for the A setpoint. The liquid line ball valve is controlled by a modulating motor (4MTR). The mod motor is positioned by the microcomputer, which is responding to cooler refrigerant level via a liquid level transducer, and compressor discharge superheat by means of the discharge pressure and temperature measurements If cooler level is sensed to be low by the transducer, the mod motor is driven open. If the level is high, the mod motor drives the valve closed. A drop in discharge superheat below a value determined by the microcomputer causes the modulating valve to close, lowering the liquid level in the cooler High Sump Temperature Alarm If sump temperature rises above the sump temperature limit (220 F) for 0 seconds, an alarm is generated. The compressor is locked off and the alarm light is turned on. Resolve the problem and press RESET Control Power Loss The microcomputer can be set up to start automatically or manually after a power failure to the microcomputer. The power loss B setpoint is factory set to 0.0 to allow automatic start after a control power loss. To select manual reset, set power loss B setpoint to.0. In this case, a power loss alarm will be stored by the microcomputer and RESET must be pressed to start Low Pressure Cut-off (Microcomputer) This function protects the unit from operating at abnormally low cooler refrigerant pressure. The microcomputer will shut down the compressor when cooler pressure falls below the low pressure setpoint and turn on the alarm pilot light. A low pressure alarm Cooler Freeze Shutoff (Microcomputer) will be recorded by the microcomputer. Reset by pressing the RESET button on the microcomputer. Standard setpoint is 58 psig for water systems. If the leaving chilled water temperature drops below the freeze setpoint, the microcomputer will shut down the unit and store the freeze alarm. After solving the problem, press RESET on the microcomputer to clear the alarm High Pressure Cut-off (Microcomputer) This function protects the compressor from operating at abnormally high discharge refrigerant pressures. The microcomputer will shut down the compressor when condenser pressure reaches the high pressure setpoint, and turn on the alarm indicator lamp on the control box. The high discharge pressure alarm will be recorded by the microcomputer. Reset by pressing the RESET button on the microcomputer. Setpoint is 250 psig. 8

20 4.5.5 Low Oil Pressure Alarm (Microcomputer) A low oil pressure alarm is triggered by one of the following conditions: ) The compressor is on and oil pressure is less than 25 psid for 0 seconds, or 2) The oil pump is on and the compressor has not started within 50 seconds. off the compressor and oil pump, and turn on the alarm light. The low oil pressure alarm code will be stored in the microcomputer. When the problem is resolved, press RESET to clear the alarm. See Section regarding oil change. If either of the above conditions occur, the microcomputer will lock Sump Heater Control The three oil sump heaters are controlled by two relays (3CR, 4CR). When the oil pump is turned on, all of the sump heaters are de-energized (3CR and 4CR are energized). When the oil pump turns off, 3CR is de-energized and two of the heaters turn on. If sump temperature is less than Heater Temperature setpoint B (45 F), 4CR is also de-energized and the third heater turns on. If sump temperature rises above Heater Temperature setpoint A (50 F), 4CR is energized and the heater turns off Compressor Starter Failure A compressor starter failure is generated if any of the starter safety contacts open. The contacts must be wired in series and connected to the control panel as shown on the wiring diagram. Safety devices on the starter may include compressor overload, under voltage/phase failure, ground fault, shorted SCR detector, etc. When one of these contacts opens, digital input 5 turns on and the compressor is locked off on a compressor starter alarm. The alarm light is turned on. Resolve the problem and press RESET Oil Pump Overload Protection The oil pump overload contacts are wired into the control panel as shown on the wiring diagram. If these contacts open, digital input 6 turns on and the compressor and oil pump are locked off on an oil pump overload alarm. The microcomputer also turns on the alarm light. Resolve the problem and press RESET. If seal oil temperature rises above the oil temperature limit (30 F) for 4 minutes, an alarm is generated. The compressor and oil pump The control power relay feeds power to the compressor control circuit. After power-up, the relay is closed to allow normal compressor control. The computer will open this relay if it detects that the compressor contactor auxiliary switch stays closed for 5 seconds when the computer is commanding the compressor to be off. The computer determines that the auxiliary switch is closed if the compressor If the computer measures an analog value that is far beyond normal operating values, the compressor is shutdown. The computer then stores the alarm code corresponding to the specific sensor High Seal Oil Temperature Alarm Compressor Power Control (No Stop Alarm) are locked off and the alarm light is turned on. Resolve the problem and press RESET. contactor digital input (typically #) is displaying ON rather than OFF. A No-Stop alarm would then be stored in the alarm history. This would indicate that either a hardware problem is forcing the compressor to run when it should not or that the contactor status is not being monitored correctly. When the problem is resolved, press the RESET key to allow the machine to start Sensor Alarm Shutdown that caused the alarm. Any of these alarms indicate a problem in the analog measurement system. After the problem is resolved, the RESET key must be pressed. The following is a description of each sensor alarm: ) Leaving water temperature error is triggered if sensor reads higher than 90 F for 0 seconds. 2) Suction pressure transducer error is activated if sensor reads less than -20 psig for 0 seconds. It is also triggered if leaving water temperature is less than 60 F and suction pressure reads higher than 50 psig for 0 seconds. 3) Discharge pressure transducer error is triggered if dis charge pressure reads higher than 390 psig or lower than 5 psig for 0 seconds. 4) Oil pressure transducer error is generated if the sensor reads higher than 350 psig, or lower than 5 psig, or if differential is greater than 20 psid for 5 seconds. This alarm will also trigger if the oil pump is off and oil differential is outside of the 0±5 psid band for 5 minutes. 5) Sump temperature sensor error is triggered if the sensor reads higher than 280 F or lower than 0 F for 0 seconds. 6) Seal oil temperature sensor error is generated if the senso reads higher than 280 F or lower than 0 F for 0 seconds 9

21 TABLE 5 HCFC-22 PRESSURE/TEMPERATURE PROPERTIES (PSIG-F) PRESS TEMP PRESS TEMP PRESS TEMP PRESS TEMP PRESS TEMP PRESS TEMP

22 Slide Valve Error (Microcomputer) A slide valve error will be generated if the feedback potentiometer measures a value below -0% or above 0% for 45 seconds. The alarm will also trigger if the oil pump is running with the compressor off and the slide reading does not fall below 8% within 45 seconds. When this alarm occurs, the compressor will be locke doff and the alarm light turned on. Check for proper operation and calibration of the potentiometer. Clear the alarm by pressing RESET Liquid Line Mod Motor Error (Microcomputer) A mod motor error will be generated if the feedback potentiometer measures a value that is more than 8% away from the target value for 45 seconds. This indicates that there is a problem with the mod motor or feedback potentiometer reading. When this alarm occurs, the compressor will be locked off and the alarm light turned on. Clear the alarm by pressing RESET Compressor Starter Error (Microcomputer) The microcomputer monitors the compressor starter failure contacts with a digital input (#5). If these contacts open at any time (digital input turns on), the compressor will be locked off on a compressor starter error. The alarm light will also be turned on. Resolve the problem and press RESET Oil Pump Starter Error (Microcomputer) The microcomputer monitors the oil pump starter with two digital inputs (#687). If the oil pump overload relay opens, the oil pump starter error is triggered. This error is also triggered if the oil pump auxiliary switch does not close (digital input 7 turns off) within 3 seconds of a pump start command. If this alarm occurs, the compressor will be locked off and the alarm light turned on. Clear the alarm by pressing RESET Chilled Water Reset (Optional) If desired, the chilled water temperature can be raised automatically by a 0-5 VDC analog signal provided by an external controller. The reset signal must be between 0 VDC and 5 VDC, with 0 VDC being no reset and 5 VDC being maximum reset. The maximum temperature reset (increase) desired must be stored in CWR MAX setpoint B. For example, to raise the chilled water setpoint from 44 F to 50 F (6.0 difference) with a 5 VDC input, a 6.0 is stored in CWR MAX setpoint B. CAUTION: The voltage input must not exceed 5.0 VDC. Shielded cable should be used for the signal wires with the shield connected to ground only at one end Demand Limiting Input (Optional) If demand limiting is desired, a 0 to 5 volt DC signal must be supplied to the Demand Limit terminals shown on the wiring diagram. The ground lead of the signal should be connected to Ground Terminal and the positive lead should be connected to the Demand Limit Terminal. Supplying 0 volts will have no limiting effect, and 5 volts will have maximum limiting. The Demand Limit setpoint is used to determine the maximum amount of limiting the voltage supplied to Demand Limit analog input will have. If the Demand Limit setpoint is set to 0.0, there will be no limiting, and if set to 0.0, there will be maximum limiting. The Demand Limit setpoint can be set anywhere between depending on the amount of Demand Limit desired. The Demand Limit works by automatically lowering the HOLD and UNLOAD amp limits for the compressors. This does not change the amp limit setpoints. The microcomputer takes the signal supplied to the Demand Limit analog input, the value held in the Demand Limit setpoint, and the amp limit setpoints to calculate the amount of limiting to take place. To calculate the value for the Demand Limit setpoint for a desired Demand Limiting current with 5 volts supplied to Demand Limit analog input, use the following equation: ((Amp Limit (B)-Desired Limit Current)/Amp Limit setpoint (B)) x 0 This Demand Limiting will only unload compressors. It will not turn them off. CAUTION: Do not feed in a voltage higher than 5.0 VDC. Shielded cable should be used for the 5 volt signal with the shield connected to ground only at one end Suction Pressure Load Limiting If the suction pressure gets close to the low pressure limit, the microcomputer performs load limiting to reduce the possibility of a low pressure trip. When suction pressure drops below the low pressure limit plus 4 psig, the compressor will not be allowed to load. If suction pressure drops below the low pressure limit plus 2 psig, the compressor will unload until suction pressure rises. 2