8.0 Table of Contents. Monitoring system WIREM

Transcription

1 Table of Contents Table of Contents 8.1 System description General system description Principle of operation Measurement principle 8.2 Planning, inspection plans Planning, sensor loop plan Inspection plans, weld seam plans 8.3 U89A monitoring device Description of device, technical data Description of device, sheet Procedure in case of malfunction Electrical diagram, wiring Option: Remote control transmission

2 8.100 General system description In the majority of cases, district heat pipes laid underground are now equipped with operational monitoring systems. The benefits are that damage can be detected at an early stage and easily located. Together with the appropriate monitoring devices, monitoring wires foamed into the heat insulation at the factory perform a wide variety of tasks. Operational reliability and safety are increased, and costs of damage are limited. The following BRUGG pipe systems are factory-equipped for monitoring with the resistance reference measuring method () as standard: FLEXWELL district heating cables, PREMANT district heating pipe and CASAFLEX district heating pipe; BRUGG STEEL CASING PIPE can also be equipped for this purpose on request. (On request, PREMANT district heating pipe can be supplied with different monitoring wires). and BRANDES are compatible systems. The technology makes it possible to carry out a large number of functions with the help of the monitoring wires and devices: Monitoring heat insulation for moisture - already possible when the pipe is being installed. Supply of informative measurement data on the condition of the heat insulation. Contact between monitoring wires and inner pipe, break-offs or interruptions anywhere in the circuit are differentiated and displayed. During operation, the entry of moisture - for example through weld seam faults, non-tight joints or external damage - can be measured, signalled and located, not only in the area of the joint but continuously throughout the entire length of the pipe. Checks for failures and faults can be carried out thanks to a dedicated device function, with a corresponding display. Shaft bottom sensors connected to the monitoring wire loop can trigger an alarm if water enters. Alarm signals are passed on via outputs for external alarm devices, electronic registration or forwarding of measurement data / additional contact statuses. Depending on the requirements for network size and data availability, a suitable system can be selected from the range of measurement, monitoring and locating equipment based on the modular principle. Device combinations range from manual entry of measurement data about the status of the heat insulation and manual fault location (device U89 A) through to fully automated monitoring and fault location with remote signalling, test inquiries via dialog electronics, storage of measurement data and electronic data transmitters to computers and printers in central management systems.

3 Principle of operation Monitoring wires The monitoring wires (sensor wire and feedback wire) are positioned continuously in the heat insulation of the pipe, between the outer and inner pipes. On PREMANT and CASAFLEX, the wires are positioned parallel to the inner pipe, approximately in the middle of the heat insulation, but in FLEXWELL district heating cable, they are positioned parallel and next to one another in a helical configuration, at a defined distance from and around the inner pipe. Structure of sensor wires 1. Perforations at regular intervals for moisture contact 2. PTFE insulation, colour: red 3. NiCr wire Structure of feedback wires 1. Copper wire 2. FEP insulation, colour: green Measuring principle for monitoring The technical basis for measurement, both for monitoring and location, is the resistance reference measuring system () which operates according to the principle of the unloaded voltage distributor. A defined voltage is applied between the sensor wire positioned parallel with the pipe in the heat insulation, and the pipe (see picture). If the insulation resistance that is present there drops due to the entry of moisture, an increase in voltage is measured on the comparator resistance in the upstream monitoring device, thereby triggering a signal. In addition to the sensor wire, another FEP-insulated copper wire known as the 'feedback wire' is used for the actual monitoring. The two wires make up a sensor loop (see the picture) which can be a maximum of 1000 meters in length, enabling 1000 meters of pipe to be monitored. Branch lines starting from the sensor wire in the main pipe are 'looped in', i.e. sensor wires 'in' and feedback wires 'back' (see picture). Monitoring principle Sensor wire [red] Structure of sensor loop Sensor wire [red] Feedback wire [green] Pipe axis S Loop Feedback wire [green] Sensor loop including branch I Insulation Monitoring device The comparator resistance defines the signalling threshold at the same time. Monitoring of the heat insulation is handled by a special sensor wire (see the picture). This wire is protected against direct metallic contact by a temperature-resistant PTFE insulation. The moisture contact with the NiCr wire is established through perforations in the PTFE insulation, thereby enabling continuous monitoring of the entire pipe section. For monitored pipe networks with a pipe length of over 1000 meters, the network is subdivided into monitoring sections of a maximum of 1000 meters, and individual sensor loops are formed from them. An appropriate monitoring device can be assigned to each monitoring section. In addition, the perforations allow a differentiated evaluation of the intensity of moisture faults, across the entire monitorable spectrum from 'dry' at over 50 MΩ to 'wet' at less than 10 kω insulation resistance.

4 Measurement principle Measurement principle for location In order to locate the moisture or contact faults (insulation faults), a location voltage (U) is applied to the sensor loop. At the start of the sensor loop, between the sensor wire and the pipe, a measurement is taken of voltage component U1; this is measured over the insulation fault on the sensor wire. However, the voltage component is not measured in volts but as a percentage of the total voltage, so it represents the result of the location. Since the sensor wire has a very high series resistance of 5.7 Ω/m and the feedback wire is close to zero ohms, the following relation is obtained: Location of an interruption in the sensor loop Whereas the interruption of the sensor loop as such is signalled immediately on automatic systems, the location of the fault point must be carried out manually, using different methods. The most widespread measuring method is the runtime method,which has proven its merits in these cases. If a wire is broken off, recourse can be had to a simple capacitance measurement method. In order to prevent subsequent fault sources, the integrity of the sensor loop should be ensured during the installation stage through continuous control measurements and manual checks on the strength and stability of wire connections. U1 R1 x % L1 = = = U R 100 % L U = total voltage U1 = voltage component R = total loop resistance R1 = loop resistance component x % = location result L = total pipe length L1 = fault distance The intensity of the insulation fault (insulation resistance) has no influence on the accuracy of the location; this is because the device concept takes account of the intensity. Measurement principle for location Location unit x % Moisture sensor Sensor wire [red] U U1 Feedback wire [green] 100 %

5 Planning Sensor loop plan Planning Sensor loop plan Planning of the monitoring system is carried out in parallel with planning of the pipe network. Attention should be paid to the length of a monitoring circuit (max m pipe per device) and the division into individual monitoring circuits. The devices may be placed centrally in a building. For subsequent planned network extensions, consideration may be given to accompanying (parallel) cables which can be laid in the pipe trenches at the same time. BRANDES monitoring system CrNi wire (red) Cu wire (green) TT 1.5 mm 2, or U mm Length 9 m: screened cable Wiring by electrician Wiring between BRUGG boxes in the building by electrician Measurements taken (results) Current flow (contact) resistance (DR) R = 5.7 Ω/m Insulation resistance (IR) Stage BS-MH-2 Flow Return Flow Return 2219 Ω 2220 Ω 0 =^ > 50 MΩ 0 =^ > 50 MΩ

6 Inspection plans, weld seam plans Inspection plans are required so that faults can also be measured above ground after location. Accurate plans make it easier to locate and diagnose the error message. Weld seam plans have proven to be best for this purpose. Inspection plan Weld seam plan Measurements taken (results) Pipe Standard L Bend [m] PRE m 0.5 x 0.5 PRE m 0.65 x 0.65 PRE m 0.65 x 0.65

7 Device description U89A Technical data Device description Function The device monitors the electrical insulation resistance between the signalling wire and the pipe (earth). At the same time, an interruption in the signalling wire or a short circuit to earth (< 5 kω) is signalled. The short-to-earth signal can also be used for shaft monitoring by connecting a level switch (for example EHS - JOLA 6M, Otto Fischer AG) between the direct wire feedback and the pipe. The device is suitable for installation in the switch cabinet and also for surface mounting. Surface mounting Button and 2 signal lamps are positioned on the device. Lamp green: red: in operation Fault Installation in switch cabinet An additional button and two signal lamps must be built into the cabinet door for operation. Fault If the electrical insulation resistance is undercut (damp insulation) in case of an interruption or short circuit to earth (shaft monitoring), a horn, lamp or central alarm system is activated. At the same time, the fault lamp lights up on the device or the cabinet door, as follows: Insulation is damp Interruption in monitoring loop Short circuit to earth; shaft monitoring with float switch Please contact BRUGG Pipesystems immediately in case of a fault!

8 Device description U89A Alarm output for external fault display The device has an alarm output to supply an acoustic signal transmitter, a lamp or a central alarm system. Acknowledge Press the double function button (device test + acknowledge button) to switch off the alarm output. The fault lamp will remain lit until the fault is rectified. Device test The device is maintenance-free. Nevertheless, we recommend that a monthly function check is performed. Press the button to simulate a fault. This checks the entire electronic system. The fault lamp must be lit in this case. The alarm output can be blocked or switched through during the test, using the built-in switch on the print. The switch should be moved to the desired position during installation. Technical data Voltage supply 220 V 50 Hz Voltage tolerance +/ 10% Power consumption 1.5 VA Output High-power contact Switching power max. 250 V AC 5 A (alternating current) max. 30 V AC 5 A (direct current) Cable infeed 6 laterally positioned Perbunan cable bushings 2 break-out openings in the housing base Type of connection Connection screws with gripper plates, max. 2 x 1.5 mm² Type of protection IP 40 Ambient temperature 10 to + 40 C Max. loop length 0 to 10 kω (0 approx m) Housing dimensions A 150 Break-out for wall fixture Ø 4.2 mm Break-out for clip fixture on 35 mm standard rail, DIN Clips in device View A

9 Procedure in case of malfunction U89A Possible fault causes Fault Possible cause 1. Green lamp not lit No mains voltage 50 ma fuse on print faulty Important Before opening the device, turn the main switch off. 2. Fault lamp (red) is lit Contact Brugg immediately! a) continuously Insulation in pipe is damp b) flashing Interruption in monitoring loop (in pipe or boxes) c) flashing Short circuit to earth in case of shaft monitoring with level switch intermittently (water in shaft) Device test without pipe system Procedure Fault lamp display 1. Remove loop, terminals must flash 2. Connect terminals must go out 3. Press button (device test) must light up 4. Connect terminals 1, must flash intermittently If all 4 statuses are correct, the cause should be sought in the pipe system (boxes, connection pipes).

10 Electrical diagram U89A Wiring Important: Turn the main switch off before opening the device

11 Option Remote control transmission U89A Version for remote control transmission e.g. Ridat Rittmeyer Device U 89 A is also suitable for computer-controlled remote control transmission. The cabinet door circuit is omitted in this case. These outputs are wired by a change on the print, as follows: Terminals 9 to 13 Logical statuses R1 R2 Everything OK I I Insulation is damp 0 0 Short circuit to earth in case of shaft monitoring with level switch. 1 0 Signalling wire has a short circuit to earth Interruption in loop 0 I R R2 9 The functions of the mains and fault lamp(s) on the device, and the "external fault" (terminals 6 to 8) are unchanged. A remote transmission relay contact can be used to test the device or acknowledge an "external fault".