Page 61 - Sace Emax 2 Catalogue

PROTECTION TRIP UNITS 3/37

03
Second protection against earth fault (ANSI 50GTD/51G & 64REF): whereas with Ekip Touch the user
protection zone has to choose between implementation of the protection G by internal current sensors (calculating the
∆ Y vector sum of the currents) or G ext external toroids (direct measurement of the earth fault current),
Ekip Hi-Touch offers the exclusive feature of simultaneous management of both configurations by two
64REF
independent earth fault protection curves. Owing to this characteristic, the trip unit is able to distin-
guish a non-restricted earth fault and then activate the opening of Emax 2, from a restricted earth
fault, and to thus command the opening of the medium voltage circuit breaker.
Another possible configuration is with the residual current protection replacing the Gext protection,
whilst 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 thus detect if 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 distri-
bution portion to be identified in which the fault occurred and to disconnect it while maintaining the
operation of the rest of the installation.

Zone selectivity for protection D (ANSI 68): enables the possibility to interconnect circuit breakers so
Generator
that, in the event of a fault, the fault area can be rapidly isolated. Disconnection only occurs at the level
close to the fault and operation to the rest of the operation continues uninterrupted. The function is
LOAD B
particularly useful in ring and grid installations where, in addition to the zone, it is also essential to de-
fine the flow direction of the power that supplies the fault. It is possible to enable directional zone se-
LOAD A
Forward lectivity alternatively to the zone selectivity of the protections S and G, and in the presence of an auxiliary
power flow FAULT
supply.
Start-up function for protection D: enables higher trip thresholds to be set at the outgoing point, as
available for protections S, I and G.

Second protection against undervoltage and overvoltage (UV2 and OV2 – ANSI 27 and 59): enables
t
U9 two minimum and maximum voltage thresholds to be set with different delays in order to be able to
discriminate, for example, between voltage dip transients due to the start-up of a motor and an actual
t9 U16 fault.

t16
V

Second protection against underfrequency and overfrequency (UF2 and OF2 – ANSI 81L and 87H):
t
f17 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
f12 t17 opened when the second threshold is reached.

t12
f