Main switch status protection functionality
Main Switch Supervision function is the custom-
ized control feature to respond to different opera-
tion position of a MNS withdrawable module and
ensure a safe operation with MNS switchboard.
The rotary handle of a MNS module has built in po-
sition indications which include main switch ON/
OFF and test position ON. The positions are one
or another and not impossible to overlapped. (FIG
48)
Main switch status function in M10x provides in-
teracting protection features during module oper-
ation, e.g. turning from ON to OFF or turning from
OFF to test position.
—
48 Operation position of a MNS module
To have a complete main switch protection func-
tion, the main switch status indication and test
switch position status are expected to be hard-
wired through digital inputs of the device.
There may be scenarios that only one indication is
available, either main switch status or test switch
status, M10x responds in different ways under such
conditions.
Scenario 1 Main switch status and test switch po-
sition are both monitored by M10x
When motor is under running state (current de-
tected), if the main switch status is observed
changing from ON to OFF before a stop command
is received, M10x trips the motor with ' Main
switch status message. If test switch position ON
is observed, M10x also trips the motor with ' cur-
rent feedback trip' message.
When motor is under test running state ( under test
with no current detected), if main switch status is
observed changing from OFF to ON, M10x trips the
motor with ' main switch status' message. If test
switch position changes to 'OFF', M10x stops the
motor.
When motor is under stopped state, if both main
switch status ON and test switch ON are observed, a
trip message 'main switch status' is issued.
0 5 . PR OT EC T I O N F U N C T I O N S 59
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