Ratio Test
The ratio is defined as the number of turns in the secondary as compared to the number
of turns in the primary.
Apply one volt per turn to the secondary of the CT under test. Raise voltage slowly
while observing meters. When one volt per turn has been reached on the secondary
voltmeter, one volt should appear on the primary meter. If the CT saturates before one
volt per turn is reached, apply a smaller voltage which is a convenient fraction of one
volt per turn. (e.g. .5v per turn). The Primary voltmeter should read the chosen fraction
of a volt. If a multi-ratio CT is being tested, the selector switch can be placed in the
"External Meter" position. The primary voltmeter can be used to read the voltage
between taps on the secondary winding while a known voltage per turn is applied to the
winding, either between taps or to the full winding.
CAUTION: TO PROTECT AGAINST INSULATION FAILURE, DO NO
EXCEED MORE THAN 1000 VOLTS ON ANY OF THE
SECONDARY WINDINGS OF THE CT UNDER TEST.
Leads should be connected to the test set EXT VOLTS binding posts only when the
selector switch is in the EXT METER CONNECTION position.