MCCB-250 USER’S MANUAL REV 2
13
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
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