The Earth Leakage Relay is a microprocessor based electronic protection device designed to recognize low level leakage or unbalanced currents due to insulation loss on conductors or equipment that must be protected. The measure of the leakage currents is obtained by the use of the ring-type current transformer FRER cod.TDC.. or TDA… . All circuit conductors to be protected shall go through the CT.
The microprocessor carries up several functions, such as:
• Trip current adjustment 30 mA to 30 A divided in 3 ranges: 30÷300 mA, 300mA÷3 A, 3÷30A.
• Trip delay time adjustment instantaneous to 5 sec divided in 2 ranges: inst.÷0,5s, 0,2÷5s
• One or two operating trip relays.
• Output relays test.
• Manual (local or remote) or programmable automatic reset.
• Continuous control of wiring connection between the relay and the CT: output relays will be activated if a wiring
interruption occurs.
The wide current range allows easy selection of precise trip current values, in order to maintain the value of the so called contact voltage below 50V, as required by the CEI 64-8 standard. The relay, thanks to its internal ltering, is immune to external disturbances. Its function is also guaranteed with alternate sinusoidal and continually pulsating dierential currents, which are applied abruptly or rising slowly (type A).
Technical data
current setting range 30mA...30A in 3 campi / ranges
current accuracy +0/- 20% dal/from 20% al/to 100% f.s.
delay setting range 0,1...5 sec in 2 campi / ranges
delay accuracy ±10% del valore impostato/of the set value
operating frequency 47...63Hz
third harmonic / attenuation 88% @ 150Hz