ABB ZX0 - Switchgear Operation; Panels with circuit-breakers and three position disconnectors

Manual ZX0 HB 600 en - Revision 05 | 37
The three switching positions of the three position disconnector,
“connecting”, “disconnecting” and “preparing for earthing” are
clearly defined by the mechanical structure of the switch. Con-
necting and disconnecting the operating current and earthing are
performed exclusively by the circuit-breaker (figures 4.1.1 and
4.1.2). Figures 4.1.3 to 4.1.8 show the switching sequence for
earthing of a busbar section using the sectionalizer and riser, on
the basis of an example switchgear installation.
In order to avoid maloperation, the operating mechanisms are
mechanically or electrically interlocked, and as an option also
electrically interlocked between different panels.
Fig. 4.1.1: Earthing a feeder and cancelling the earthing
Fig. 4.1.2: Connecting and disconnecting a feeder panel
− The three position disconnector (disconnector and earthing
switch function) can only be operated when the circuit-
breaker is open. The earthing switch can only be operated
when the disconnector is open. The disconnector can only
be operated when the earthing switch is open.
&
See the order documents for the conditions of optional
panel to panel interlocks.
Feeder
disconnected
Connection
prepared
Feeder
connected
Connect feeder
Disconnect feeder
Feeder
disconnected
Earthing
prepared
Feeder
earthed
Earth feeder
Cancel feeder earthing
4. Operation
− All activities in connection with operation of the switchgear
require compliance with EN 50110 standard or relevant
national regulations regarding the operation of electrical
installations (see also page 6).
− Always make sure that switching operations have been
completed before performing the next switching operation.
4.1 Panels with
circuit-breakers and
three position
disconnectors
4.1.1 Notes on earthing of a feeder
panel or system section
When the feeder panels or section of the system has
been earthed by operating the earthing switch and
circuit-breaker (figures 4.1.1, 4.1.2 and 4.1.5 to 4.1.9),
secure it to prevent cancellation of earthing as follows:
Switch the mcbs for the circuit-breaker release circuit and for the
motor-operated mechanism of the three position switch in the rel-
evant panel off.
Lock the low voltage compartment door or where appropriate the
mechanical OFF button for the circuit-breaker.
Affix a sign to the panel to indicate that earthing has been per-
formed.