PROTECT ION TR I P UNI TS
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Second protection against ground fault (ANSI 50GTD/51G & 64REF) : whereas with Ekip Touch the user has to choose between implementation of the protection G by internal current sensors (calculating the vector sum of the currents) or G ext external toroids (direct measurement of the ground fault current), Ekip Hi- Touch offers the exclusive feature of simultaneous management of both configurations by two inde- pendent ground fault protection curves. Through this characteristic, the trip unit is able to distinguish a non-restricted ground fault which activates the opening of Emax 2, from a restricted ground fault which activates the opening of the medium voltage circuit breaker. Another possible configuration is with the residual current protection replacing the Gext protection, while the G protection remains active. The residual current protection is activated in the presence of the residual current rating-plug and of the toroid. Directional overcurrent (D – ANSI 67) : the protection is able to recognize the direction of the current during the fault period and detect whether the fault is upstream or downstream of the circuit- breaker. The protection, with fixed time trip curve (t=k), intervenes with two different time delays (t7bw and t7fw), according to the current direction. In ring distribution systems, this enables the distribution portion to be identified in which the fault occurred and to disconnect it while continuing to operate the rest of the installation. Zone selectivity for protection D (ANSI 68) : provides the ability to interconnect circuit breakers so that al- lows rapid isolation of the fault area in the event of a fault. Disconnection only occurs at the level closest to the fault while the remainder of the operation continues uninterrupted. The function is particularly useful in ring and grid installations where, in addition to the zone, it is also essential to define the flow direction of the power that supplies the fault. It is possible to enable directional zone selectivity alternatively to the zone selectivity of the protections S and G, and in the presence of an auxiliary supply.
protection zone
∆
Y
64REF
Generator
LOAD B
LOAD A
Forward power flow
FAULT
Start-up function for protection D: enables higher trip thresholds to be set at the outgoing point, as avail- able for protections S, I and G.
Second protection against undervoltage and overvoltage (UV2 and OV2 – ANSI 27 and 59) : enables two minimum and maximum voltage thresholds to be set with different delays to enable differentiation, for example, between voltage dip transients due to the start-up of a motor and an actual fault.
t
U9
t9
U16
t16
V
Second protection against underfrequency and overfrequency (UF2 and OF2 – ANSI 81L and 87H) : enables two minimum and maximum frequency thresholds to be set simultaneously. For example, only an alarm can be set to be tripped when the first threshold is reached, and the circuit breaker can be set to be opened when the second threshold is reached.
t
f17
f12 t17
t12
f
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