Page 62 - Sace Emax 2 Catalogue

3/38 SACE EMA X 2 LOW VOLTAGE AIR CIRCUIT-BRE AKERS

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Description of protection functions

Dual setting of protections: Ekip Hi-Touch can store a set of alternative parameters for all protections.
This second series (set B) can replace, if necessary, the default series (set A) by an external command.
The command can be given when the network configuration is edited, for example when an emergency
source is activated in the system, changing the load capacity and the short-circuit levels. Another typi-
cal application is protecting the operator opposite the switchgear against the electric arc. In this case,
protection delays are minimized to safeguard the operator (Set A), whereas in the absence of an opera-
tor the protections are set to ensure selectivity with the circuit breakers downstream (Set B). It is pos-
sible to activate series B by:
• Digital input available with an Ekip Signalling module;
• Communication network, by means of one of the Ekip Com communication modules;
• Directly from the Ekip Hi-Touch display;
• By a settable internal time, after the circuit-breaker has closed.

L1 L2 L3 Differential ground fault (Rc - ANSI 87N): protects against internal earth fault on generator winding. It
is required that the toroid hugs the active conductors and the ground conductor. Rc protection is inte-
grated by a dedicated residual current rating plug and the external toroid.

The specific functions for generator protections are described below. For each of these it is possible to
choose the operating mode: active, only alarm or deactivated. All the voltage and frequency protec-
tions also operate when the circuit- breaker is open, enabling the fault to be identified before the clos-
ing of the circuit breaker.

Voltage controlled overcurrent protection (S(V) - ANSI 51V): protection from maximum current with a
t
1 constant trip time (t = k) that is sensitive to the voltage value. The set current threshold, following a volt-
age drop, decreases by steps or linearly.
Ks
t20

I
KsxI20 I20
In step mode (controlled mode) the protection is tripped at the set threshold (I20) if the voltage is above U,
K
whereas it is tripped at the lower threshold of the factor Ks (I20 * Ks) if the voltage is below U.
1
Ks

V
UIU
On the other hand, in linear mode (restrained mode) two voltage limits are selected within which the
K
protection is tripped at the set threshold (I20) reduced by the factor K corresponding to the measured
1 voltage. The variation of the factor K is proportional to the voltage, and for voltages greater than the
upper threshold (Uh) the threshold I20 works, whereas for voltages below the lower threshold (UI) the
Ks
minimum threshold (I20 * Ks) applies.
V
UI Uh