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22.4 Fault Diagnosis
Type and condition of
Defect/Probable cause
abnormality
1. The circuit breaker
1. The closing operation cannot be
is not closed.
performed.
1.1 The OFF-lock device (CYL,
CAL, Padlock) is not
released.
1.2 The circuit breaker is not in
the correct position.
1.3 The drawout handle is
inserted.
1.4 Voltage is not applied to the
UVT.
1.5 Voltage is not applied to
control circuit terminal.
2. The closing operation is
performed.
Tripping (OFF) is performed
simultaneously with the closing
operation.
3. ON button is damaged or
cannot be pushed.
4. Manual reset button protrudes.
5. The circuit breaker body greatly
tilts.
2. The circuit breaker
1. The contact does not open even
is not opened.
after pushing the OFF button.
2. The SHT does not operate.
3. OFF button is damaged or
cannot be pushed.
3. Unusual
1. Loosing of the main circuit
temperature rise
terminal screws.
2. Main circuit junction is
damaged.
3. The contact resistance of the
contact has increased.
(DC resistance value is to be
the catalog value × 1.5 or less)
4. Load current is too large.
4. Electronic Trip
1. Trip at rated current or less
Relay (ETR)
Abnormality
4.1 Unexpected trip
2. Trip when the load starts
3. Trip due to noise or surge
4.2 Abnormal
1. The circuit breaker does not trip
characteristics
even when an over current
flows.
2. The characteristics by the field
test device Y-2005 is
abnormality.
Investigation/Primary treatment
Release the OFF-lock device.
(CYL, CAL, Padlock)
Change the drawout position to
"CONNECT", "DISCONNECT", or
"TEST".
Pull out the drawout handle.
Apply voltage to the UVT.
Examine the circuit.
S1 and S2 of the
Please contact Mitsubishi Electric.
Please contact Mitsubishi Electric.
Push the Manual reset button to
reset.
Check the installation conditions
on page 19 and install the circuit
breaker correctly.
Please contact Mitsubishi Electric.
(Note)
1. If the voltage is not applied,
2. In the case of voltage applied,
Please contact Mitsubishi Electric.
Retighten. (M12 45±5 N·m)
Please contact Mitsubishi Electric.
Clean the contact surface (by
using wire brush).
Check the load equipments.
Check the load current and
characteristics setting of the ETR.
Check the characteristics by the
field test device Y-2005.
Check the inrush current and STD/
INST setting of the ETR.
Shift the setting of the ETR to
upper level (temporary use).
Check connection of the frame
ground terminal P4 .
Check the load current and
characteristics setting of the ETR.
Check the characteristics by the
field test device Y-2005.
Check the field test device setting.
Treatment
examine the control circuit.
the circuit breaker has some
failure. Please contact
Mitsubishi Electric.
Secondary treatment
Please contact Mitsubishi Electric
if closing cannot be performed
even after completing the primary
treatment.
Refer to the section " 10.3.2
Opening" if there is an abnormality
of the UVT.
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Please contact Mitsubishi Electric
if discoloration of the conductor or
the terminal molding is noted.
ー
Please contact Mitsubishi Electric
if the temperature does not fall
even after cleaning the contact
surface.
ー
Please contact Mitsubishi Electric
if there are any abnormalities.
Please contact Mitsubishi Electric
if there are any abnormalities.
Reduce noise or surge at the
source. Add a surge absorber, etc.
Please contact Mitsubishi Electric
if there are any abnormalities.
Please contact Mitsubishi Electric.
E-51
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