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Due to RMS continuous product improvement policy this information is subject to change without notice. 4M300/Issue K 10/08/21 - 3/6
Figure 3
Operation
Changing the 4M300 Test Block system from the normal service
condition to the secondary injection test condition is achieved in
three steps shown in figure 3 below:
TOP VIEW
REAR VIEW
Shown with isolation plug fitted to short terminals 13 & 14 (4M300-B model only)
NORMAL SERVICE CONDITION
SECONDARY INJECTION TEST CONDITION
Circuit isolating bar not yet engaged
4M320 terminals touch
Automatic CT shorting engaged
Circuit isolating bar engaged
Equipment side circuits isolated from live side circuits
WITHDRAW DC AUXILIARY ISOLATION PLUG (4M300-B model only)
DC auxiliary supply link between terminals 13 & 14 is removed
Step 1 - DC AUXILIARY SUPPLY ISOLATION
Step 2 - AUTOMATIC CT SHORTING
Step 3 - CIRCUIT ISOLATION
Auxiliary supply isolated - 4M300-B
CT shorting links engaged
INSERT 4M320[B] TEST PLUG
Automatic shorting of CT's wired to terminals
22, 24, 26 & 28
4M320[B] Test Plug fully inserted
4M300-B Test Block Terminal Status
Other
ODD
terminals
LIVE
SIDE
13
13
13
13
21
21
21
21
23
23
23
23
25
25
25
25
27
27
27
27
Other
EVEN
terminals
EQUIPMENT
SIDE
14
14
14
14
22
22
22
22
24
24
24
24
26
26
26
26
28
28
28
28
Al
l c
irc
ui
ts
is
ol
at
ed
4M320-A Manual
4M320-B Automatic
Equipment side & live side
contacts shorted
