L&T Electrical & Automation OMEGA, Manual

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59
Matrix
Modules
E A R T H L E A K A G E ( E L ) M O D U L E
In industrial installations, the current leakage can happen to earth because of
the following main reasons:
i) Current leakage through phase to earth insulations
ii) Leakage of current through phase to earth leakage capacitance
Due to the high insulation resistance the leakage current magnitude remains
low in terms of milliamps or micro amps. Assuming that the phase-to-earth
insulation resistance in an LV network is just 1 Mega-ohm(*), then the leakage
current to earth will be (240V/1 Mega-ohm) 240 microamperes. But, generally
the phase-to-earth insulation resistance would be much higher than just
1Mega-ohm, normally a few tens or even hundreds of Mega-ohms. Thus, the
leakage current to earth will be a further fraction of the micro-ampere or even
nano-amperes. As human body’s sensible current is more than 1 milli-ampere,
this remains un-sensed by a human being coming in contact with the earthed
frame of an LV electrical installation.
Any leakage current above 300mA can result into fire in electric installations. In Industrial areas especially in mining
application the earth leakage protection becomes critical for the fire safety.
Omega Matrix Earth Leakage module has Earth leakage current monitoring range of 300mA to 30A. The EL module
communicates on CAN bus with the Matrix releases which can be set in Alarm, Trip or “Both”mode.
S o m e m o r e f e a t u r e s o f E L m o d u l e :
• "NO" contact for external indications (24V DC/240V AC, 6A)
• Standalone module
• Dip switches for configuring pickup and delay settings
• Self-diagnostic check for module healthiness check
*As per Indian Electricity rule, 1956, Rule No. 48(ii) For Medium & Low Voltage Installations, Voltage at a pressure of 500 V applied
between each live conductor and earth for a period of one minute, the insulation resistance of medium and low voltage installations shall
be at least 1 Mega ohm.