EARTH LEAKAGE DETECTOR

FOR MEDIUM VOLTAGE SYSTEMS

The M-series earth leakage detectors are developed for the protection of hazardous conditions caused by high resistance earth faults on the 1000 to 3300 Volt Power Systems.

The following two types of detectors are now available.

• The M1050 has an eart fault trip level of 1 Amp and with a trip delay of between 3 and 10 seconds and are used for overhead lines where long trip delays are required.(Short trip delays will enable nuisance tripping to hapen,caused by temporary faults on the line).
  
  
• The M0501 has an earh fault trip level of 0,5 Amp and a trip delay of less than 100 milliseconds. The M0501 are used mainly for cable applications,where instananeous tripping are required,such as in the case where an underground cable is accidentally hit or pierced by a metal object.

When a fault condition is detected,the detector activates other standard low voltage off-the-shelf isolating equipment,thus isolating the power to the step transformer.

Both units required a specially desinged 100/1 CT for detecting the earth leakage current.The CT's can be connected in two modes of operation.The one mode of operation is where it is used as a balanced core CT on the secondary side (high voltage side) of a step up transformer.In this mode,it will detect any off balances in the summed load current.The second mode of operation is where the earth wire, of a grounded star point ,feeds through the CT.In this application the CT will detect any earth current flowing through the earth wire.

The detector dimensions are 70x72x30 (millimetres) and clips on to a standard DIN rail.

DNS Electronics CC
164 Sonja Street
Doringkloof
0157
South-Africa

Tel:(012) 667-2189
Fax: (012) 667-2189



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