Mitsubishi Electric UM 10t, Instruction Manual

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Inspection of Power Supply System (Measurement of lowest voltage at start up)
Inspection procedure Judgment and remedy
1. Turn off the power switch to the trolley line.
Connect a voltmeter or electric tester near the
insulated shaft of the trolley pole.
2. Turn on the trolley line power switch. Read
the voltage.
3. Take this measurement between the phases
(R-S and S-T).
Acceptable if all the three phases are read 200-220 V (up
to 240 V for 60 Hz). If not, change the tap connection on
the transformer.
If the readings of the three phases vary, check the
transformer wiring.
4. Press the "UP" pushbutton with the voltmeter
connected and the power switch on as above.
Due to the high starting current lasting for a
moment, the hand on the voltmeter first
swings into the low range then swings back
into the high range. Read the lowest voltage.
5. Take measure in step 4 above on all the three
phases.
Acceptable if all the three phases are 180 V or more.
Can be used if all the three phases are 170 V (60 Hz) or
160 V (50 Hz) or more.
Cannot be used if the voltage is below the above value.
(For a detailed description of the corrective method, refer
to Item 10 described in the previous table.)
If three phases are not balanced, the cause of unbalance is
cause (1) of Item 10 described in the previous table. In
this case, repair the problem part.
(Note)
The voltage readings in step 4 above represent the lowest values when the electromagnet attracts
the elements or the motor starts up. Judge the situation based on these voltage readings.
When you contact us, please let us know the power supply voltage (see above inspection step 2)
and the lowest voltage (see above inspection step 4).
(Instructions for measurement of inverter power supply current)
1. During lowering operation, regenerative energy returns from the hoisting motor to the
inverter. This may cause power current not to flow.
2. When lifting/lowering very light load or no load at all, little electric power is consumed.
Since power is in this case supplied through two high-voltage power wires, no current may
flow through the remaining one wire.
3. During lifting operation, the inverter input current may fluctuate. This is because this
current is not sinusoidal.