EFZ

FAULT RELAY

Recognition of changes in phase sequence

Recognition of phase loss

Recognition of asymmetry in voltage of three phases

Fast disconnection in case of fault

Capability of selecting energization time after fault comection

Having display signals for different faults and normal status


 

Principles of Operation

This relay is designed for protection against earth connection. Basically. when network current is in balance. resultant of currents passing through load wires is zero. For example. . all the current which reaches to consumer from phase just retums from null in a single-phase two-wire network. It is also the same in

three-phase three-wire or four-wire networks. Anyhow. traveling current in wire would be fixed with symmetric or asymmetnc loads. But when earth con- nection happens. some of traveling current is grounded while not retuming through the network wires. Considering that all the wires of consumer should pass through the transformator core associated with the device (core bal- ance current transformator). this imbalance would be revealed and relay commands the disconnection.

When supply voltage and output of CT associated with the device are connected to terminals Al. A2 and CT and leaking current isin allowed range. the device intemal relay opens (intemal contact of terminal 15 to 18 is established) and PWR and FAULT signals would be on and off respectively.

When earth leaking curent is beyond that adjusted by AMPERS potentiometer handle. device starts timing. Then, at the end of time adjusted by DELAY potentiometer handle. FAULT signal gets ON and intemal relay closes (intemal contact of terminal 15 to 18 is made). If earth cunent leakage decreases into the allowed range during the above adjusted time. relay remains unchanged.

After FAULT signal gets ON. if earth curent leakage 6 under the allowed limit. FAULT signal gets OFF and device intemal relay opens (intemal contact of terminal 15 to 18 established).

If J fenminals are separated from each other. device will start quiomatically after every fault occurence and its correction. If J terminals are connected together. device should be restarted by RESTET button every time after fault occurence and its correction.

2 Signals

PWR: Input supply display

FAULT: Fault condition display

Installation and Start-Up

Supply voltage 6s connected to terminals Al and A2. All the consumer’s wires should pass through the device associated CT. CT output should be connected to CT terminals of earth fault relay. Terminals 15. 16 and 18 are device intemal relay contact points which have to be put in series with control circuit if required for example. to activate an alarm or to discon- nect the main contactor’s command. The limit from which current leakage should not exceed is set by adjustment potenti- ometer handle (CAMPERS). The delay time duration in device internal relay closing is set by delay time adjustment potentiometer handle (DELAY). This is adjustable in range of 1 to 30 seconds.

Technical Specifications

Supply Voltage: 220 VAC + 10%

Network Frequency: 50 +5 Hz

Internal Loss: About 3 W

Leakage Current Limit: 0.3-6. 1-204

OFF Delay: 1 to 30 seconds. adjustable by DELAY potentiometer handle

Output Relay: Single C/O Contact

Contact Current: 6 A. 220 VAC- 6A. 28 VDC