627-500
33
INTERLOCKS
The switchgear assembly may include key or
mechanical interlocks on the doors, switch
operators, etc. of some modules. Typical
interlock schemes—including precautionary
measures that must be taken to maintain lock
integrity—are discussed below. For the types
and locations of interlocks that are included
on the switchgear assembly, and for operating
descriptions of special interlocking schemes
that may have been specifi ed, refer to the “CDA”
and “RD” drawings.
Mechanical Interlocks
Mechanical interlocks are included on all PMX
Switchgear modules with switches or fuses.
These interlocks prevent the module door from
being opened when the switch is closed and
the switch from being closed when the module
door is open. For more information see the S&C
instruction sheet on operation included with
the switchgear.
Ç
DANGER
Check the functional operation of all
mechanical interlocks.
Failure to check
these interlocks may result in personal
injury or death.
Key Interlocks
Interrupter switches, whether manually
operated or power operated by S&C Switch
Operator—Type PM
, may include optional
key interlocks that guard against paralleling of
the power sources. See Figure 28. If such key
interlocks are included, do not attempt to close
a source interrupter switch unless the other
source interrupter switch is open.
Interrupter switches with fuses, whether
manually operated or power operated by
S&C Switch Operator —Type PM
, may include
key interlocks that guard against opening the
module door unless all source interrupter
switches are open (preventing access to the
fuses). If such key interlocks are included, do
not attempt to open the module door unless all
source interrupter switches are open.
Figure 28. Key interlock.
Ç
CAUTION
Use of undue force in an attempt to operate
switches contrary to the correct sequence
dictated by the key interlock scheme may
damage handles or latching mechanisms.