Megger MOM2, Руководство пользователя

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30 MOM2 ZP-BD03E BD0333FE
5 OPERATING INSTRUCTIONS
5.8 Testing on circuit
breakers having a current
transformer in the loop
If there is a current transformer (CT) in series with the
breaker contact to be tested then it is advisable to make
some basic checks.
Encapsulated or dead tank breakers are the most common
types which have a current transformer in the loop.
The technical reason is that the CT must be saturated before
it is possible to get a reliable result. To get a transformer
saturated it needs time and current or an open secondary
winding.
A CT included in the circuit may influence the DC resistance
reading. The CT need to be in saturation not to influence
the DC resistance measurement. The time required to drive
the CT in saturation depends on current level and secondary
side burden, the time is usually several seconds if secondary
side is shorted.
If possible make a visual check to be sure that there is no
current transformer in the loop. If this is not possible like in
encapsulated breakers then make the following check:
1]
Make two tests, one with 0.1 second and one
with 3 seconds setting. If the values are equal
then there is no current transformer in the
loop.
If you get different readings it might be a need for a
“workaround”.
1]
If possible increase the current and / or test
time.
2]
Increase the burden on the current trans-
former by opening the secondary winding
or connect a 5 to 10 ohm resistor across the
winding.
3]
Repeat the measurement several times in
the same direction until a stable value is
achieved.
5.9 Trouble shooting
Problem Solution
Headset does
not work Check that it is paired to MOM2
Check on MOM2 that Bluetooth
is enabled
Error messages
Message Cause Remedy
"OL" Bad connection
/ resistance out
of measurement
range Check cables and connec-
tions
Warning sign
on display and
the battery
charge indica-
tor blinks The batteries
cannot charge
the capacitor Charge the batteries
Note: It might be possible
to proceed and make some
tests if it is realistic to select
a test position that requires
less power (shorter measur-
ing time).
Warning sign
on display A thermal
protection has
tripped. Turn off the MOM2 and let it
cool down.