Inspection; Required Tools And Material; Procedure - ABB BUE Maintenance Manual

2. Inspection

The inspection mainly consists of a visual check of the
motor-drive mechanism once a year while the transformer is
in service. It is recommended to perform the inspection of
the motor-drive mechanism and the other parts of the tap-
changer at the same time. See the respective maintenance
guide.
In the motor-drive mechanism, the following points are to be
checked:
– Motor and counter
– Heater
– The counter's value
– Visual check of toothed belt

2.1 Required tools and material

The following equipment is required for the inspection:
– Set of screw drivers

2.2 Procedure

WARNING
This work must be carried out from ground level since
the transformer is energized!
WARNING
Before starting any work inside the motor-drive
mechanism, the auxiliary power must be switched off.
N. B. The motor, contactors and heating element may
be energized from separate sources.
1. Open the cabinet door of the motor-drive mechanism and
turn the selector switch to the LOCAL position. Then turn
the control switch to the RAISE (LOWER) position.
12 Maintenance guide BUE/BUL2 | 1ZSC000498-ABH en, Rev. 1
2. Check that the motor works properly, the position indicator
increases (decreases) one step and the counter advances
one step for each operation. Record the counter's value.
The counter shows the number of operations run by the
tap-changer (the overhaul schedule can be determined
with the help of this information).
3. Turn the control switch to the LOWER (RAISE) position for
1-2 seconds. Check that the motor also works properly in
that direction, the position indicator decreases (increases)
one step and the counter advances one more step. Reset
the drag hands.
4. Check the emergency stop. Trigger a RAISE or LOWER
impulse and after about one second, press the emergency
stop. The operation should be interrupted. Reset the
emergency stop by turning the knob clockwise and by
switching on the protective motor switch. The started
operation should now be completed. Operate back to the
service position.
5. Check the ground fault protector (option).
If the motor-drive mechanism is equipped with an outlet,
the ground fault protector should be tested by pressing
the test knob on the outlet.
6. Disconnect the incoming auxiliary power.
7. Open the control panel.
8. Check by feeling with a finger that the elements have been
functioning.
9. Close the control panel and reconnect the incoming
auxiliary power.
10. Complete the inspection by turning the switch to the
REMOTE position and closing the cabinet door.