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Problem
5. The 2nd-stage limit
switch operates.
6. Wire rope is cut.
7. The hoist does not
start even if the
pushbutton is
pressed.
8. The hoist lowers and
stops during hoisting
9. The hoist stops
suddenly during
hoisting.
10. Power is applied to
the traversing motor,
but the motor growls
and takes a longer
time (2 sec. or more)
to start.
11. The hoist suddenly
stops during lifting
or lowering
operation.
Cause
(1) Incorrect connection of power supply line
(2) Wire rope wound reversely
(3) Although the use of the no-load high-speed
function has been specified, the upper limit stop
point has not been set. Or the upper limit set
position is too high.
(1) The rope catches on something during hoisting.
(2) Corrosion due to chemicals
(3) Use of badly worn wire rope
(1) Pushbutton defective, or pushbutton cable
broken
(2) Incorrect wiring of power switch, fuse, contactor,
or pushbutton, imperfect contact of trolley line,
loose screws, etc.
(3) The inverter does not give 3-phase output.
(4) No signal is returned from the sensor, or one of
the rotation signals (signals for 2 phases) is not
returned from the RRS board.
(5) The hoisting motor torque is insufficient for
overload, and the hoist stops.
(6) The hoisting motor overheats due to too frequent
use, the torque drops, and the hoist stops.
(1) Overload
(2) Hoisting motor overheat
(3) Hoisting motor wire breakage
(1) Inverter trip due to overvoltage caused by
hoisting an overload.
(2) Inverter overvoltage tripping is caused due to rise
in the resistance value that is caused by
temperature rise of the discharging resistor due to
too frequent use.
(3) Disconnection of discharging resistor
(1) Electric resistance is high due to wiring, switch
or trolley contact failure or loosened screws.
(Voltage drop at start)
(2) Wires too thin or long
(3) Supply voltage too low.
(4) Electromagnetic brake not released.
(5) Defective electromagnetic brake coil.
(1) The 1st-stage limit switch functions.
(2) Inverter trip due to too low supply voltage
(3) Hoisting brake works.
(4) Inverter trip due to overload or ground lifting
(5) Fall caused by overload is detected.
(6) Malfunction due to noise.
- 40 -
Remedy
(1) Exchange the phases R and T
of the power supply.
(2) Set the upper limit correctly.
(3) Set the upper limit to the
proper position.
(1) Handle and maintain the rope
properly. Replace the
defective wire rope.
(Use the Mitsubishi genuine
wire rope.)
(1) Repair, replace, or cut out.
(2) Check, and repair. See the
expanded connection diagram.
(3) Check the inverter.
(4) Check and replace the RRS
board. Check the signal line
(microphone cord) for dis-
connection.
(5) Reduce the load.
(6) Use the hoist at appropriate
intervals.
(1) Reduce the load.
(2) Use the hoist at appropriate
intervals.
(3) Check, and repair.
(1) Reduce the load.
(2) Use the hoist at appropriate
intervals.
(3) Check, and repair.
(1) Check, and repair.
(2) Change the wiring in accord-
ance with the selection table.
(3) Change the transformer taps.
(4) See Item 14.
(5) Replace the coil.
(1) Lower the load.
(2) Change the transformer taps.
(3) See Item 14.
(4) Re-examine the lowering
method and load.
(5) Re-examine the lowering
method and load.
(6) Fit a noise filter to the 3-phase
power supply.
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