Specifications

G22
GE Limitamp
®
Medium Voltage Motor Control
Components
G
Description
Test Power Interlocks (TPI) and Control Power Interlocks (CPI)
are standard. The function of the CPI contacts is to disconnect
the secondary of the internal control power transformer
before the main isolation switch can be operated. This is
important because the isolation switch is rated for non-load
break duty only, and is tested to switch transformer-mag-
netizing current only. The TPI contacts function to transfer
control power from the internal control power transformer
(when the isolation switch handle is in the ON position), to
external test power (when the switch handle is in the OFF
position) and to prevent backfeeding the control power
transformer from test power.
TSW is a selector switch that is provided as standard to switch
from internal control power to remote test power source. It
is provided as a back-up to the TPI contacts to provide an
additional layer of protection against accidental backfeed of
the control power from test power.
CPI contacts are linked to the Handle Latch Release (pusher)
bar on the external handle assembly. In the released state
(pusher not depressed) the CPI contacts are in the CLOSED
state and the ON-OFF isolation switch handle is locked in
either the ON or OFF position. If the main contactor is open,
the pusher bar may be depressed. Once the pusher bar is
depressed, the CPI contacts change to the OPEN state and the
external ON-OFF handle, that operates the controller isolation
switch, is released.
The TPI contacts are linked to the ON-OFF handle position such
that the TPI contacts change state as the handle position is
changed.
TPI, CPI & TSW