Page 83 - SACE Tmax XT - Catalogue

PROTECTION TRIP UNITS 3/49

03
Zone Selectivity Protection blocks
The function allows multiple circuit-breakers be- With the Ekip Connect software six blocks are
longing to the same installation to be connected available for some protections, which is useful for
together, in order to coordinate the trip units and deactivating the protection based on program-
to reduce the tripping times in the case of protec- mable events. In particular:
tions S, G, S2 and I. Thus, in the event of a failure: • four blocks are associated with the
• the circuit-breaker closest to the fault trips programmable states A, B, C and D
• the other circuit-breakers are locked for a • one block is associated with the start-up (present
programmable time. for protections that have a StartUp function);
Each circuit-breaker that detects a fault reports it • one block, not present for frequency
to the circuit-breaker upstream; the circuit-breaker protections, is associated with the checking
that detects the fault but does not receive any the measured frequency.
communication from those downstream opens Each block is independent and has its own activa-
without waiting for the set delay to elapse. tion command. The protection is deactivated for
It is possible to enable zone selectivity if a fixed- a time equal to the duration of the event itself:
time curve has been selected and the auxiliary • if the programmed event occurs (true), in the
supply is present. case of state-based blocks
• if the StartUp function is active and the start-up
threshold is exceeded (the active block for the
StartUp Enable • set start-up time), whenever the
The function modifies the threshold of the pro- StartUp block function is enabled.
tection for a period that can be set by the user, • if at least one frequency measured is outside
avoiding unwanted trips due to high inrush cur- the range 30…80 Hz, in the case of a frequency
rents of certain loads (motors, transformers, based block.
lamps). The starting phase lasts 100ms to 30s
and is recognized automatically by the trip unit: Directional Zone Selectivity
• at the closing of the circuit-breaker with a The Zone Selectivity function allows multiple cir-
self-supplied trip unit; cuit-breakers belonging to the same installation
• when the peak value of the maximum current to be connected together in order to coordinate
exceeds the set threshold (0.1…10 x In) with an the trip units and reduce tripping times, but with
externally supplied trip unit. some important differences:
A new start-up is possible after the current falls • it is to be used in installations with a ring circuit
below the threshold. This function can be acti- • it allows tripping to be managed and
vated with a fixed time protection function (t = k). coordinated according to the power flows
Moreover, the I3 startup threshold must be higher (determined by the direction of the current), in
than the I2 startup threshold. order to minimize dispersion of energy.
It works as an alternative to S and G Zone Selec-
tivity.