(5) Connect the earth test lead (MODEL7244A) to the earth terminal of the
circuit under test. Then, place the tip of remote probe (line) to P terminal
of the string.
Confirm that the voltage in the circuit under test is not high (usually less
than 50V). If high voltage is detected, impaired insulation is suspected.
The instrument may give live circuit warning while the subject string is
generating voltage, but can perform measurement where the voltage is
positive dc and less than the rated measurement voltage.
Note: Select the insulation resistance function for PV systems.
DANGER
● Never make measurements on a circuit in which earth potentials of
600 V or higher exist.
CAUTION
● Always turn off the breaker of the measurement line. The instrument
cannot make measurement on circuits energized with AC voltage or to
which negative DC voltage is being applied. Measurement in such live
circuit conditions may damage the instrument.
Display example
Voltage
Fig. 7-3
Solar inverter
Earth terminal
Disconnection
OFF
N terminal
P terminal
String (Solar cell array)
Black
Red
switc
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