SYSTEM OVERVIEW Pollution monitoring of high voltage insulators in electrical power transmission and distribution systems, switchyards and substations is essential in order to minimise the risk of power outages due to electrical breakdown of insulators otherwise known as flashover. Such events are caused by the contamination of insulators in service by airborne soluble and non-soluble pollutants. Under moist ambient conditions the soluble pollutants become conductive and significantly diminish the insulating properties of HV insulators. The LCMS provides a means for measuring surface leakage currents and records values that are meaningful for evaluation of the insulator surface pollution level. This is done directly on-line and in near real-time. Characteristics and summary parameters of the leakage current waveforms are recorded allowing the analysis to be carried out. High pollution events are likely to lead to flashovers. Warnings of conditions that exceed preset limits are provided by external alarms (voltage free contacts), and logged in historical data records as significant events. The capability to monitor the ambient temperature and humidity, in selected areas of the site, is also provided. This functionality is important for correlative analyses. To assess the levels of insulator contamination during a long dry spell, when the soluble pollution deposition is not conductive, the LCMS is provided with an optional ability to dampen the insulator, or a group of insulators, with a fine atomised mist of clean water, which is periodically sprayed on the insulators surface at time-intervals determined by the user. During periods of high ambient humidity or rain, the water spraying system is automatically deactivated. All operational parameters (settings, states and status) are made available for recording and display at a remote monitoring and control site. LCMS Site Installation - conceptual diagram
LCMS PERFORMANCE SPECIFICATION 1. ELECTRICAL (LEAKAGE CURRENT MEASUREMENT) 1 No of Leakage current inputs independent isolated and protected current monitoring inputs 100VAC isolation when a 2-wire current sensing cable/connector is used. (Note that the ground side of each connector is connected to the LCMS case) 2 Sensitivity Leakage Current Sensitivity is dependent on the value of the sensing resistor and the input gain setting. Nominal sensing resistor is 0ohm See items,, and resistor value of ohm) resistor value of 10ohm) resistor value of 0ohm) 1 6 Current Range 7 9 Current Resolution (sensing resistor value of 0ohm) Current Measurement Noise (sensing resistor value of 0ohm) Current measurement Dynamic Range 10 Measurement accuracy 0.% 2000 ma peak 200mA peak 20 ma peak 2 ma peak Gain = 1 Gain = 10 Gain = 100 Gain = 1000 (0 db) (20 db) (0 db) (60 db) 1 ma peak 1000 ma peak (depending on gain setting) Gain = 1000 down to 1 ( steps) 0.2 ma peak 200 ma peak (depending on gain setting) Modes (selectable) : Manual - gain selection at base station Auto Ranging 6 µa for 200 ma FS 0.6 µa for 20 ma FS <0.1 µa for 2 ma FS <0.1 µa for 0.2 ma FS 20 µa rms for 200 ma FS 2 µa rms for 20 ma FS <0.2 µa rms for 2 ma FS <0.2 µa rms for 0.2 ma FS Instantaneous : >60 db Measurement : >120 db 11 Non-linearity 0.2 % of reading 12 Basic Sampling rate ks/sec per channel (factory default) 1 Input signal bandwidth Hz to 6.1 khz for Gain = 1 Hz to 6.1 khz for Gain = 10 Hz to. khz for Gain = 100 Hz to 0.9 khz for Gain = 1000 Gain = 1000 down to 1 ( steps) Gain settings : 1, 10, 100 and 1000. Readings are corrected for gain value. Gain values are reported in measurement data. Based on 16-bit conversion and 10V range for ADC (0 µv resolution) Due to input amplifiers and circuit noise. Instantaneous - any fixed gain Measurement - over full current range Based on sensing R tolerance and conversion resolution This allows accurate capture of up to 0 th harmonic of periodic mains waveforms Allows capture of transient events down to 200 µsec (sampling rate limited) 1 Leakage Current Analysis Based on continuous collection of waveform data at selected sampling rate, data filtering & analysis with thresholding and reporting at required time intervals. Internal signal processing and analysis algorithms reduce the volume of data transmitted to the base station. 1 Summary Data Collection Interval 0 = 1second 1 = seconds 2 = 10 seconds = 0 seconds = 1 minute = minutes 6 = 10 minutes 7 = 0 minutes 16 Alarm outputs Voltage-free contact closure Configurable parameter LCMS internal relays. Accessed via the AUX connector. 1 The 0ohm LC ranges are for accurate laboratory tests and also for monitoring of composite insulators where a small leakage current and surface arcing can irreversibly damage the insulator surface and severely degrade its pollution performance. 2
2. MAXIMUM RATINGS 1 Supply Voltage + 0 VDC 2 Input Leakage current signals Built-in Input Overvoltage and surge Current Protection Transient Protection (leakage current inputs) Analogue Input Signals (Temp & Humidity) Linear measurement range : 10 V peak (indefinitely) Overload limits : 12.V rms (17.7 Vpk) for minutes (0 ma peak) 2 V rms (0 ma) for 1 second 90V Gas Arrester followed by 1V over voltage protection (SIDACtor) Differential input : 20kA (/20µs impulse), 6 A rms for 1 second Common mode input : 1200V peak Input ±10V, 0 ma 0/60 Hz power frequency For 0ohm Rsense Initial input protection against insulator flash-over current with input circuit protection against over-voltage. Current limited by conductor rating, GDT and Rsense Voltage limited by input isolation 6 Digital Input Signals Logic input (differential) ±7.V, 0mA Optically isolated 00 V common mode isolation 7 Control Output Relay output 200V, 0. Amp 100V to ground Cold contact - Rating : 200 V switching 0.A, 1A carry, contact R 0.1ohm Temperature -20ºC to +0º C Ambient Protection required if exposed to direct sunlight 9 Humidity 9% non-condensing. POWER SUPPLY REQUIREMENTS Fully isolated supply required no mains 1 Supply Voltage 7 0 VDC earth connection to the output. Can be supplied from AC mains using a DC power supply /pack 2 Power Consumption 1 W nominal Supply current depends on applied voltage Transient Protection 100W transient input voltage suppression. TEMPERATURE AND HUMIDITY TRANSDUCER 1 2 Temperature measurement range and precision Relative Humidity range and precision -10 to +7 C ±0.% 10 to 9% ±% Dependent on the separate external temperature and Humidity sensor module (mounted in solar radiation protective shield).
. MECHANICAL SPECIFICATION 1 Remote module size 200mm x 10mm x 16mm (LxWxH) Excluding antenna (top mounted) 2 Solar radiation protection Remote module weight kg Body material Ingress Protection IP6 2 X 2 mm stainless steel shade hat mounted on the top of the LCMS. Aluminium (extrusion grade 606 T6 sidewalls and grade 0 for top and bottom plates) 6 Mounting Flange 6mm thick with X 6mm diameter holes each side 7 Leakage current input connectors TNC type Optional solar shade is available - for protection from extreme open environment exposure. Surface treated (Chromate conversion process MIL-C-1 CLASS 1A) and use of 16 grade stainless steel fasteners for corrosion resistance LCMS remote seals and all external connectors and switches are appropriately specified. Use of stainless steel mounting bolts recommended (see item above). Each input is suitable for coaxial cable connection to monitored insulators Main, auxiliary and USB connectors Bulgin style (circular multi-pin for main & auxiliary and USB series A format) IP6 dust and moisture rated 9 Relay outputs x voltage-free relay contacts. Trigger Level1, level2, spray, and error 10 Display Window LCD display of status and measurements with LED annunciators showing key parameter status 11 External Controls Two push-button switches RESET and STOP functions 6. OPTIONAL INSULATOR WETTING SYSTEM 1 Power supply 12VDC 7. COMMUNICATIONS 1 Signal and data transmission rates Up to Mbps at ranges to 00m depending on radio path clearance and site noise In-built WiFi capability conforming to IEEE 02.11b/g standard.. EMC QUALIFICATION TESTS ITEM PARAMETER APPLICABLE STANDARD COMMENT 1 Electrostatic discharge IEC 61000--2 2 Conducted RF IEC 61000--6 Fast transients IEC 61000-- Supply voltage fluctuation IEC 61000--11 Lightning impulse IEC 61000-- 6 7 Power frequency magnetic field Damped oscillatory magnetic field Radiated RF electromagnetic IEC 61000--9 IEC 61000--10 IEC 61000--
BASE STATION SOFTWARE The LCMS uses a proprietary software suite to enable the continual monitoring of a sites LCMS installation, and to provide the warnings and alarms associated with insulator degradation due to contamination. The software is designed to run on a standard PC or laptop running the Microsoft Windows operating system. This provides the connectivity to control, configure and monitor the LCMS remote module(s) at a site, and to allow the display of the insulators individual performance and condition. When an event occurs that is in excess of the monitoring thresholds set for the insulator, the LCMS remote can be configured to capture a detailed time series of the leakage current waveform. Base Station Main Screen Base Station Results Screen Detailed Leakage Current Signal LCMS Remote Unit