Vanguard MCCB-250 User Manual
Page 16
MCCB-250 USER’S MANUAL
REV 2
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Follow the steps below to measure the CT primary and secondary currents:
a. Connect the Safety Ground to the MCCB-250.
b. Connect the Current cables from the MCCB-250 to the bus (CT primary) as shown in
Figure 4.
c. Connect the CT secondary winding to the MCCB-250
[EXT CURRENT]
input as shown
in Figure 4.
d. Turn the
[CURRENT CONTROL]
knob to zero.
e. Turn on the
[POWER SWITCH]
.
f. Hold the
[DOWN ARROW]
key to momentarily turn on the current source.
g. Turn the
[CURRENT CONTROL]
knob to set the desired current.
h. Release the
[DOWN ARROW]
key.
i. Press the
[UP ARROW]
key to select the ON+TIMER mode and to start the test.
j. Observe and record the CT primary and secondary current and the polarity displayed on
the LCD screen. A typical LCD screen display is shown below:
NOTE
The external current polarity is shown as in phase (“+” sign) or out of phase
(“-”) with respect to the MCCB-250 drive current. The CT turns ratio can be
obtained by taking the current ratio.
k. Turn off the current source by pressing the
[DOWN ARROW]
key.
986 mS 59.2CY
Ext I:-1.004 A
Drv I:20.00A