Page 58 - Sace Emax 2 Catalogue

3/34 SACE EMA X 2 LOW VOLTAGE AIR CIRCUIT-BRE AKERS

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Description of protection functions

Zone selectivity for S, I and G protections (ANSI 68): can be used to minimize circuit- breaker trip times
closer to the fault. The protection is provided by connecting all the zone selectivity outputs of the trip units
Zone 1 belonging to the same zone and taking this signal to the trip unit input that is immediately upstream.
Zone 2 Each circuit breaker that detects a fault reports it to the circuit breaker upstream; the circuit- breaker
thus detects the fault but does not receive any communication from those downstream and opens
Zone 3 without waiting for the set delay to elapse. It is possible to enable zone selectivity if the fixed-time
curve has been selected and the auxiliary supply is present.

Current thresholds: this function enables four independent thresholds to be indicated in order to en-
able corrective action implementation before the overload L protection trips the circuit breaker. For ex-
ample, by disconnecting loads located downstream of the circuit breaker that are controlled by Ekip
Signalling.

Advanced protection functions
A different operating mode can be chosen for the following protection function:
1. Active: protection enabled by opening of the circuit- breaker when the threshold is reached;
t Extremely Inverse 2. Only alarm: protection active, with only alarm indication when the threshold is reached;
t Very Inverse 3. Deactivated: protection disabled.
Standard Inverse
Extremely Inverse
t Very Inverse 8
Standard Inverse
Extremely Inverse
Very Inverse 8
Standard Inverse Furthermore, when the voltage and frequency protections are activated, they indicate an alarm status
8
I even when the circuit breaker is open so that a fault can be identified before the circuit breaker closes.
I
t I Undervoltage (UV - ANSI 27): with constant trip time (t = k), function is tripped when phase
t voltage falls below set threshold.
t U8 UV
U8 UV
t8 U8 UV
t8 V
t8 V
t V
t Overvoltage (OV - ANSI 59): with constant trip time (t = k), function is tripped when phase voltage ex-
OV
t U9 ceeds the set threshold.
U9 OV
U9 t8 t9 OV
t8 t9 V
V
t8 t9
t V
t
UF
t f12 Underfrequency (UF - ANSI 81L): with constant trip time (t = k), function is tripped when network fre-
f12 quency falls below set threshold.
UF
t12 f12 UF
t12
t12
t12 f
t12 f
t12
t f
t
t f13 OF
f13 OF
f13 t13 OF
t13 f
t13 f
f
mean
mean
U14 voltage unbalance
mean
U14 voltage unbalance
U14
U1 U2 U3 voltage unbalance
U1 U2 U3
U1 U2 U3
V1
V1
V1 senso ciclico
senso ciclico
V3 V2 senso ciclico
V3 V2
V3 V2