REV 2
MCCB-250 USER’S MANUAL
14
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
[
]
key to momentarily turn on the current source.
g.
Turn the
[CURRENT CONTROL]
knob to set the desired current.
h.
Release the
[
]
key.
i.
Press the
[
]
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
[
]
key.
986 mS 59.2CY
Ext I:-1.004 A
Drv I:20.00A