Controller for operation of evaporator on water chiller EKD 316

Controller for operation of evaporator on water chiller EKD 316 Manual

Contents Introduction... 2 Operation... 3 Survey of functions... 4 Operation... 7 Menu survey... 7 Data... 9 Connections... 9 Ordering... 9 Start of controller...10 If the superheating fluctuates...12 Check that the ETS valve closes when the supply voltage to the controller is interrupted...12 Introduction Application The controller and valve can be used where there are requirements to accurate control of superheat and temperature in connection with refrigeration. E.g.: Processing plant (water chillers) Cold store (air coolers) A/C plant Advantages The evaporator is charged optimally even when there are great variations of load and suction pressure. Energy savings the adaptive regulation of the refrigerant injection ensures optimum utilisation of the evaporator and hence a high suction pressure. The superheating is regulated to the lowest possible value. Regulation Independent superheat regulation The superheat in the evaporator is controlled by one pressure transmitter P and one temperature sensor S2. The expansion valve is with step motor of the type ETS. Fitting the "S4" temperature sensor is optional, but the regulation is improved by an "inner loop control" when the sensor is fitted. Functions Regulation of superheat Temperature control MOP function ON/OFF input for start/stop of regulation Relay output to alarm Valve driver (alternative use) This is where the controller receives signals from another controller, after which it controls the valve s opening degree. The signal can either be a current signal or a voltage signal. The valve can either be an ETS type or KVS type. o61 = 2 o61 = 1 Function Valve driver Battery For safety reasons the liquid flow to the evaporator must be cut off if there is power failure for the controller. As the ETS valve is provided with step motor, it will remain open in such a situation. When mounting the battery backup, the valve will close in the event of a power cut. Small capacities If the controller is used for plants with smaller capacities than an ETS 12½, a ETS 6 or Saginomiya valve type SKV, VKV or PKV can be connected. 2 Manual RS8EH802 Danfoss 11-2011 EKD 316

Operation Superheat function You may choose between two kinds of superheat, either: Adaptive superheat or Load-defined superheat MOP The MOP function limits the valve s opening degree as long as the evaporating pressure is higher than the set MOP value. External start/stop of regulation The controller can be started and stopped externally via a contact function connected to input terminals 20 and 21. Regulation is stopped when the connection is interrupted. The function must be used when the compressor is stopped. The controller then closes the ETS valve so that the evaporator is not charged with refrigerant. Relays The relay for the alarm function is an alternating relay. It is the link between terminals 24 and 25 in alarm situations and when the controller is dead. Operation You cannot operate the controller directly, but it is fixed with data communication that can be used in one of the following two ways: To connect an external display. You can then operate it using the display s control buttons To connect a system unit with MODBUS communication. It can then be operated from a PC which has AK-ST software loaded. The controller cannot be operated via AKM type system software. EKD 316 Manual RS8EH802 Danfoss 11-2011 3

Survey of functions Function Normal display Normally the superheat is shown The opening degree is displayed during manual operation or if the valve is under analogue control. Reference Unit Here you select whether the controller is to indicate the temperature values in C or in F. And pressure values in bar or psig. If indication in F is selected, other temperature settings will also change over to Fahrenheit, either as absolute values or as delta values The combination of temperature unit and pressure unit is depicted to the right. Correction of signal from S2 (Compensation possibility through long sensor cable). Correction of signal from S4 (Compensation possibility through long sensor cable). Start/stop of refrigeration With this setting refrigeration can be started and stopped. Start/stop of refrigeration can also be accomplished with the external switch function. See also appendix 1. Parameter r05 r09 r10 r12 Parameter by operation via data communication SH / OD% Miscellaneous Units (Menu = Misc.) 0: C + bar 1: F + psig Adjust S2 Adjust S4 Main Switch Alarm If there is an alarm, the LEDs on the front of the external display will flash if it is connected. The alarm relay in the controller is closed. Battery alarm Here it is defined whether the controller is to monitor the voltage from the battery backup. If there is low voltage or no voltage alarm will be given. A34 Alarm setting Batt. alarm Control parameters Injection control Valve definition n03 Valve type 0: ETS 12.5, ETS 25 1: ETS 50 2: ETS 100 3: ETS 250 4: ETS 400 5: User defined (n37 and n38 must be set) 6: ETS 6/ Saginomiya UKV, SKV, VKV, PKV P: Amplification factor Kp n04 Kp factor If the Kp value is reduced the regulation becomes slower. I: Integration time Tn n05 Tn sec. If the Tn value is increased the regulation becomes slower. D: Differentiation time Td n06 Td sec. The D-setting can be cancelled by setting the value to min. (0). Max. value for the superheat reference n09 Max SH Min. value for the superheat reference n10 Min SH Warning! Due to the risk of liquid flow the setting should not be lower than approx. 2-4 K. MOP If no MOP function is required, select pos. Off. n11 MOP (bar) (A value of 20 corresponds to Off) Start-up time for safety signal n15 StartUp time If the controller does not obtain a reliable signal within this period of time the controller will in other ways try to establish a stable signal. (A too high value may result in a flooded evaporator). The value should only be changed by specially trained staff. Signal safety during start-up n17 Start OD% The control function uses the value as start value for the valve s opening degree at each thermostat cutin. By adaptive control the controller continuously calculates a new value. The value should only be changed by specially trained staff. Stability factor for regulation of superheat With a higher value the control function will allow a greater fluctuation of the superheat before the reference is changed. The value should only be changed by specially trained staff. n18 Stability 4 Manual RS8EH802 Danfoss 11-2011 EKD 316

Damping of amplification near reference value This setting damps the normal amplification Kp, but only just around the reference value. A setting of 0.5 will reduce the KP value by half. The value should only be changed by specially trained staff. Amplification factor for the superheat This setting determines the valve s opening degree as a function of the change in evaporating pressure. An increase of the evaporating pressure will result in a reduced opening degree. When there is a drop-out on the low-pressure thermostat during start-up the value must be raised a bit. If there is pendling during start-up the value must be reduced a little. The value should only be changed by specially trained staff. Definition of superheat regulation (Ref. appendix 2) 1: Lowest permissible superheat (MSS). Adaptive regulation. 2: Load-defined superheat. The reference is established based on the line formed by the three points: n09, n10 and n22. Value of min. superheat reference for loads under 10% (The value must be smaller than n10 ). Max. opening degree The valve s opening degree can be limited. The value is set in % Number of steps from 0% to 100% open (User defined valve, n03 =5) (Automatic setting when valve is selected in n03) Spindle stroke speed (number of steps per second) (Automatic setting when valve is selected in n03) Integration time for the inner loop gain Used only when o56 = 2 The value should only be changed by specially trained staff. Miscellaneous Address/data communication The controller must always have an address. The factory-set address is 240. When an external display is connected, the display itself will find the address of the controller so that communication can take place. A display and a system unit must not be connected at the same time. The display will not be able to communicate in this situation. If the controller is to be part of a network with other controllers and a system unit, the controller's address must be within the range 1 to 200. This address must EITHER be set via a display before it is connected to the data communication and a scan of the network is performed OR the network is connected and a scan is performed. The address is then set afterwards. A new scan is performed so that the new address is known. Requirements for the installation and data communication cable are discussed in the separate document no. "RC8AC". Application mode 1: The controller receives signals from another controller and must control the valve s opening degree. 2: Superheat regulation Input signal for external control of the valve's opening degree Only used if o61 is set to 1. Definition of the signal's range. 0: No signal 1: 0-20 ma 2: 4-20 ma 3: 0-10 V 4: 1-5 V (At the lower value the valve will be closed. At the upper value the value will be fully open. There is a linear relationship between the signal and the opening degree. The height of the valve is not taken into account.) Manual control of outputs For service purposes the ETS-output and alarm relay outputs can be forced However only when regulation has been stopped. OFF: No override 1: Manual control via o45 is enabled 2: The alarm relay releases so that there is a connection between 24 and 25 (= alarm) 3: The alarm relay picks up so that there is a connection between 25 and 26 (= no alarm) n19 n20 n21 n22 n32 n37 n38 n44 o03 o61 o10 o18 Kp Min Kp T0 SH mode SH Close ETS OD% Max Max. steps (100 to 6000 step) Steps / sec (5 to 300step/sec) TnT0 sec Miscellaneous The controller can be operated via the system unit and AK service tool. It cannot be operated via AKM type system software. Unit addr. The address is set between 0 and 200. (When the address is set the system unit s scan function should be activated.) Appl. mode AI type Manual ctrl EKD 316 Manual RS8EH802 Danfoss 11-2011 5

Manual control of the ETS valve The valve s opening degree can be set manually. However, it does require "o18" to be set to "1", "2" or "3". This function must only be used for manual operation. It must not be used for external control. Working range for pressure transmitter Depending on the application a pressure transmitter with a given working range is used. This working range (say, -1 to 12 bar) must be set in the controller. The min. value is set. o45 o20 Manual ETS OD% MinTransPres. The max. value is set o21 MaxTransPres. Selection of control algorithm Depending on the application control can be carried out based on different parameters. The two possibilities are shown in appendix 3. 1=normal control 2=with inner loop regulation and S4 temperature less T0 o56 Reg. type * Refrigerant setting o30 Refrigerant Before refrigeration can be started, the refrigerant must be defined. You can select the following refrigerants: 1=R12. 2=R22. 3=R134a. 4=R502. 5=R717. 6=R13. 7=R13b1. 8=R23. 9=R500. 10=R503. 11=R114. 12=R142b. 13=User defined. 14=R32. 15=R227. 16=R401A. 17=R507. 18=R402A. 19=R404A. 20=R407C. 21=R407A. 22=R407B. 23=R410A. 24=R170. 25=R290. 26=R600. 27=R600a. 28=R744. 29=R1270. 30=R417A. 31=R422A (Warning: Wrong selection of refrigerant may cause damage to the compressor). Service A number of controller values can be printed for use in a service situation Read value of external current signal / voltage signal (Ext.Ref.) u06 Analog input Read status of input DI (start/stop input) u10 DI Read the temperature at the S2 sensor u20 S2 temp. Read superheat u21 SH Read the control s actual superheat reference u22 SH ref. Read the valve s opening degree u24 OD% Read evaporating pressure u25 Evap. pres. Pe Read evaporating temperature u26 Evap.Press.Te Read the temperature at the S4 sensor u27 S4 temp. Operating status The controller s operating status can be called forth by a brief (1s) activation of the upper button. If a status code exists it will be shown. (Status codes have lower priority than alarm codes. This means that status codes cannot be seen if there is an active alarm code. The individual status codes have the following meanings: S10: Refrigeration stopped by the internal or external start/ stop. 10 * After o56 is changed, the controller must be switched off and powered up again. Service -- DO1 Alarm Read status of alarm relay EKC State (0 = regulation) 6 Manual RS8EH802 Danfoss 11-2011 EKD 316

Operation Via data communication If you operate the controller via data communication, you must use the descriptions detailed on previous pages. Here the function is referred to in the column to the right. Via external display If you use an external display to operate the controller this must be done as follows: The values will be shown with three digits, and with a setting you can determine whether the temperature are to be shown in C or in F. (Pressure in bar or psig.) The buttons When you want to change a setting, the upper and lower buttons will give you a higher or lower value depending on the button you are pushing. But before you change the value, you must have access to the menu. You obtain this by pushing the upper button for a couple of seconds - you will then enter the column with parameter codes. Find the parameter code you want to change and push the middle button until the value for the parameter is shown. When you have changed the value, save the new value by once more pushing the middle button. Example Set a menu 1. Push the upper button until a parameter is shown 2. Push the upper or the lower button and find the parameter you want to change 3. Push the middle button and the value is shown 4. Push the upper or the lower button and select the new value 5. Push the middle button again to conclude the setting By pushing the middle button you go directly to setting Kp (n04 value). Menu survey SW =2.2x Function Fac. Application Parameter Min. Max. setting menu = o61 choise The menus from either column 1 or column 2 are shown 1 2 Normal display During regulation the actual level of superheating is displayed. (If you would like to see the expansion valve s actual opening degree, press the bottom button for about a second.) - K - During control with an analogue signal the opening degree is displayed. - % - Reference Units (0= C+bar /1= F+psig) r05 0 1 0 Correction of signal from S2 r09-10.0 K 10.0 K 0.0 Correction of signal from S4 r10-10.0 K 10.0 K 0.0 Start / stop of refrigeration r12 Off / 0 On / 1 Off / 0 Alarm Battery monitoring A34 Off / 0 On / 1 Off / 0 Regulating parameters Valve definition: 0=ETS 12½ & ETS 25, 1=ETS 50, 2=ETS 100, 3=ETS 250, 4=ETS 400, 5=User defined, 6=ETS 6, Saginomiya type UKV/ n03 0 6 1 SKV/VKV/PKV P: Amplification factor Kp n04 0.5 20 3.0/0.7 I: Integration time T n05 30 s 600 s 120 D: Differentiation time Td (0 = off) n06 0 s 90 s 0 Max. value of superheat reference n09 2 K 15 K 10 Min. value of superheat reference n10 1 K 12 K 6 MOP (max = off) n11 0.0 bar 20 bar 20 Signal reliability during start-up. Safety time period. Should only be changed by trained staff n15 0 sec. 90 sec 0 Signal reliability during start-up Opening degree s start value. Should only be changed by trained staff. n17 0% 100% 0 Stability factor for superheat control. Changes should only be made by trained staff n18 0 10 5 Damping of amplification around reference value Changes should only be made by trained staff n19 0.0 1.0 0.3 EKD 316 Manual RS8EH802 Danfoss 11-2011 7

Amplification factor for superheat Changes should only be made by trained staff n20 0.0 10.0 0.4/3.0 Definition of superheat control 1=MSS, 2=LOADAP n21 1 2 1 Value of min. superheat reference for loads under 10% n22 1 K 15 K 4 Max. opening degree Changes should only be made by trained staff n32 0 % 100 % 100 Number of steps from 0-100% opening degree (only if n03 =5 (user defined)) The display can only show 3 digits, but the setting value is 4 digits. Only the 3 most important are shown, i.e. a reading of e.g. 250 means a setting of 2500. (Automatic setting when valve is selected in n03) n37 10 (100 stp) 600 (6000 stp) 262 Number of steps per second n38 5 stp/s 300 stp/s 300 Integration time for inner loop (TnT0) n44 10 s 120 s 30 Miscellaneous Controller s address o03 0 240 240 If the valve s opening degree should be controlled with an external signal, the signal is defined as: 0: no signal, 1: 0-20 ma 2: 4-20 ma o10 0 4 0 3: 0-10 V 4: 1-5 V Manual control of outputs: OFF: no manual control 1: Manual control with "o45" enabled o18 off / 0 3 Off /0 2: The alarm relay is activated (the coil picks up) 3: The alarm relay is activated (the coil releases) Working range for pressure transmitter min. value o20-1 bar 0 bar -1.0 Working range for pressure transmitter max. value o21 1 bar 60 bar 12.0 Refrigerant setting 1=R12. 2=R22. 3=R134a. 4=R502. 5=R717. 6=R13. 7=R13b1. 8=R23. 9=R500. 10=R503. 11=R114. 12=R142b. 13=User defined. 14=R32. 15=R227. 16=R401A. 17=R507. 18=R402A. 19=R404A. 20=R407C. 21=R407A. 22=R407B. o30 0 31 0 23=R410A. 24=R170. 25=R290. 26=R600. 27=R600a. 28=R744. 29=R1270. 30=R417A. 31=R422A. Manual control of the valve s opening degree. The function can only be operated if o18 has been set to "1". This function is only for manual operation. It must not be used for a regulation function. o45 0 % 100 % 0 Selection of control mode: 1=Normal o56 1 2 1 2 = With inner loop (S media temperature less T0) Application mode. Menus blanked out so only the shaded menus are seen. See the two columns to the right. 1: Controlling a valve with an analogue signal o61 1 2 2 1 2 2: Superheat regulation Service Analog input (21-22) u06 ma (V) Read status of input DI (20-21) u10 on/off Temperature at S2 sensor u20 C Superheat u21 K Superheat reference u22 K Read valve s opening degree u24 % Read evaporating pressure u25 bar Read evaporating temperature u26 C Temperature at S4 sensor u27 C Configuration settings (n03, n37, n38, o03, o30, o56 and o61) available only when regulation is stopped. (r12=off). Valve overview n03 Valve type n37 n38 0 ETS 12½ and 25 262 1 ETS 50 262 2 ETS 100 353 3 ETS 250 381 300 4 ETS 400 381 5-6 UKV, SKV, VKV, PKV 24 The controller can give the following messages: E1 Fault in controller E24 S2 Sensor error E25 error S4 Sensor error E19 message The input signal on terminals 21-22 is outside the range. E20 The input signal on terminals 17-19 is outside the range (P0 signal) A11 A43 A44 S5 S9 S10 non Alarm message Status codes No refrigerant has been selected Check the supply voltage to the step motor Battery alarm (no voltage or too low voltage) MOP Error Refrigeration stopped r12=off Regulation 8 Manual RS8EH802 Danfoss 11-2011 EKD 316

Data Supply voltage Power consumption Input signal *)Ri: ma: 400 ohm V: 50 kohm 24 V a.c. /d.c. +/-15% 50/60 Hz, 10 VA (the supply voltage is not galvanically separated from the input and output signals) Controller ETS step motor Current signal * Voltage signal * Pressure transmitter 5 VA 1.3 VA 4-20 ma or 0-20 ma 0-10 V or 1-5 V AKS 32R Digital input from external contact function Sensor input 2 pcs. Pt 1000 ohm Alarm relay 1 pcs. SPDT AC-1: 4 A (ohmic) AC-15: 3 A (inductive) Step motor output Pulsating 30-300 ma Data communication Mounted with MODBUS data communication 0 to +55 C, during operations -40 to +70 C, during transport Environments 20-80% Rh, not condensed No shock influence / vibrations Enclosure IP 20 Weight 300 g Montage DIN rail Operation Approvals Battery backup Max. distance between controller and valve External display type EKA 164A or AK-ST via data communication and system unit EU Low Voltage Directive and EMC demands re CE-marking complied with. LVD-tested acc. to EN 60730-1 and EN 60730-2-9 EMC-tested acc. to EN50081-1 and EN 50082-2 If battery backup is used the requirements to the battery is: 18-24 V d.c. See also page 12. 50 m Ordering Type Function Code no. EKD 316 EKA 164A Superheat controller (with terminals) Display (with MODBUS communication) 084B8040 084B8563 Temperature sensor Pt 1000 ohm / Pressure transmitter type AKS 32R: Kindly refer to catalogue RK0YG ETS valves: Kindly refer to data sheet DKRCC.PD-VD1.A1.-- Connections Necessary connections Terminals: 1-2 Supply voltage 24 V a.c./d.c. 3-4 Battery (the voltage will close the ETS valve if the controller loses its supply voltage. The battery voltage must be kept disconnected from terminals 1 and 2. 5-8 Supply to step motor 9-13 Operation via data communication EITHER EKA 164A OR System unit + software It is important that the installation of the data communication cable be done correctly. Cf. separate literature No. RC8AC... 20-21 Switch function for start/stop of regulation. If a switch is not connected, terminals 20 and 21 must be short circuited. Class II Data communication ETS 6/ Saginomiya UKV, SKV, VKV, PKV Application dependent connections Superheat control 14-15 Pt 1000 sensor at evaporator outlet (S2) 15-16 Pt 1000 sensor for measuring air temperature (S4) 17-19 Pressure transmitter type AKS 32R (the signal can not be shared with other controllers) Control of the valves opening degree with analog signal 21-22 Current signal or voltage signal from other regulation (Ext. Ref.) 24-26 Alarm relay There is connection between 24 and 26 in alarm situa tions. max. 24 V, 1 A resistive Class II 1,2 3,4 21,22 Connection to earth will destroy the controller EKD 316 Manual RS8EH802 Danfoss 11-2011 9

Connection of display If the controller is to be operated from an external display, type EKA 164A, the connection must be as below: Max. distance between controller and display is 1000 m. The supply voltage to the display must be maintained at 12 V +/- 15%. See also the requirements for data communication. Connecting to networks operation via PC If the controller is to be operated from the AK-ST software programme, the connection must be as below: See also the requirements for data communication. System unit Connection to MODBUS Communication direct to MODBUS RTU protocol. Start of controller When the electric wires have been connected to the controller, the following points have to be attended to before the regulation starts: 1. Switch off the external ON/OFF switch that starts and stops the regulation. 2. Follow the menu survey on page 7, and set the various parameters to the required values. 3. Switch on the external switch, and regulation will start. 4. Follow the actual superheat on the display. 10 Manual RS8EH802 Danfoss 11-2011 EKD 316

Appendix 1 Interaction between internal and external start/stop functions and active functions. Internal External Regulation Sensor Configuration Start/stop start/stop (DI) monitoring settings Off Off => Off No Yes Off On => Off No Yes On Off => Off Yes No On On => Yes Yes No Appendix 2 The two types of regulation for superheat are, as follows: Adaptive superheat (n21 = 1) Load-defined superheat (n21 = 2) Regulation is here based on the evaporator s load by means of MSS search (MSS = lowest permissible superheat). (The superheat reference is lowered to the exact point where instability sets in). The superheat is limited by the settings for min.and max.superheat. The reference follows a defined curve. This curve is defined by three values: the closing value, the min. value and the max. value. These three values must be selected in such a way that the curve is situated between the MSS curve and the curve for average temperature difference Tm (temperature difference between media temperature and evaporating temperature. Setting example = n22=4, n10=6 and n09=10 K). Appendix 3 Regulation algorithms for the superheat. There are several algorithms to choose between. Reg.type = 1 (o56=1) This regulation algorithm is used for the classical method and is recommended for known applications e.g. for earlier installations with a Danfoss controller. For a start the values for Kp, Tn and Td can be set to values corresponding to the earlier ones. Reg.type = 2 (o56=2) We recommend this setting if the superheating is to be regulated with precision. Here the S4 and T0 temperature is part of an inner loop control. The regulation algorithms require that a temperature sensor be fitted in the chilled medium. The temperature sensor is connected to input S4 and mounted in the chilled medium after the evaporator. (Danfoss calls a sensor S4 when it is mounted in the refrigerant after the evaporator). EKD 316 Manual RS8EH802 Danfoss 11-2011 11

If the superheating fluctuates When the refrigerating system has been made to work steadily, the controller s factory-set control parameters should in most cases provide a stable and relatively fast regulating system. If the system however fluctuates this may be due to the fact that too low superheat parameters have been selected: If adaptive superheat has been selected (n21 = 1): Adjust: n09, n10 and n18. If load-defined superheat has been selected (n21 = 2): Adjust: n09, n10 and n22. Alternatively it may be due to the fact that the set regulation parameters are not optimal. If the time of oscillation is longer than the integration time: (T p > T n, (T n is, say, 240 seconds)) 1. Increase T n to 1.2 times T p 2. Wait until the system is in balance again 3. If there is still oscillation, reduce K p by, say, 20% 4. Wait until the system is in balance 5. If it continues to oscillate, repeat 3 and 4 If the time of oscillation is shorter than the integration time: (T p < T n, (T n is, say, 240 seconds)) 1. Reduce K p by, say, 20% of the scale reading 2. Wait until the system is in balance 3. If it continues to oscillate, repeat 1 and 2. Check that the ETS valve closes when the supply voltage to the controller is interrupted This control is performed if the controller is connected to battery backup. The battery will make the step motor move to the end stop and thus close the valve. Battery information The battery voltage must be 18-24 V DC and the capacity can be determined from the following information: During standard operation the battery uses approx. 17 µa With power supply and closed valve the battery uses approx. 17 µa Power supply fails and the valve closes: 120 ma for up to 7 seconds. Installation considerations Accidental damage, poor installation, or site conditions, can give rise to malfunctions of the control system, and ultimately lead to a plant breakdown. Every possible safeguard is incorporated into our products to prevent this. However, a wrong installation, for example, could still present problems. Electronic controls are no substitute for normal, good engineering practice. Danfoss will not be responsible for any goods, or plant components, damaged as a result of the above defects. It is the installer's responsibility to check the installation thoroughly, and to fit the necessary safety devices. Particular attention is drawn to the need for a force closing signal to controllers in the event of compressor stoppage, and to the requirement for suction line accumulators. Your local Danfoss agent will be pleased to assist with further advice, etc. List of literature Installation guide for data communication RC8AC Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss reserves the right to alter its products without notice. This also applies to products already on order provided that such alternations can be made without subsequential changes being necessary in specifications already agreed. All trademarks in this material are property of the respecitve companies. Danfoss and Danfoss logotype are trademarks of Danfoss A/S. All rights reserved. FC-SPMC 12 Manual RS8EH802 Danfoss 11-2011 EKD 316