
44
1ZSE 5492-118 en, Rev. 4
For BUE:
Run the motor-drive mechanism and check again that the red mark on the brake disc stops
within the tolerance limits, see Fig. 13.
If it is out of tolerance, charge the springs more or less by tightening or loosening the two
adjustment nuts on the brake assembly. Tightening makes the brake disc stop earlier, loos-
ening makes it stop later. The nuts should be adjusted equally.
For BUL:
Run the motor-drive mechanism and check that the centre of the notch in the cam disc
stops within ±2 mm from the centre of the roller on the brake arm, see Fig. 14. If it does not
stop within the tolerances, adjust the breaking force with the adjusting screw in the lower
end of the brake arm. Loosen the contra nut. Tightening the screw (clockwise) makes the
stop earlier and loosening the screw (anticlockwise) makes the stop later. Tighten the contra
nut after the adjustment.
Check that the position indicators in both the motor-drive mechanism and the on-load tap-
changer show the same position. Operate one step and check that the on-load tap-changer
follows the motor-drive mechanism.
Operate the driving mechanism electrically between the end positions. Check the end stops.
When trying to operate it electrically beyond the end position, the motor should not get
started. Check the mechanical end stop by trying to hand crank it beyond the end position.
After a couple of turns on the hand crank it should be mechanically stopped. Hand crank
back to the end position. Operate the on-load tap-changer electrically to the other end posi-
tion and repeat the test procedure above.
WARNING
The transformer should in no case be energized with an end stop out of order.
8.3 Electrical tests on transformer
Acceptance tests on the transformer or commissioning can now be performed.
8.4 After energizing
WARNING
Before any work is carried out on the on-load tap-changer:
Make sure that the transformer is disconnected and that earthing is properly carried
out. Obtain a signed certificate from the engineer in charge.
8 Electrical connection and testing