7 Fault elimination
Maschinenfabrik Reinhausen GmbH 2020
128
4983703/01 EN
VACUTAP
®
VV-Ex
7.1 Tripping the protective relay and re-commissioning the
transformer
WARNING
Danger of explosion!
Explosive gases in the protective relay can deflagrate or explode and result
in severe injury or death.
► Wait 15 minutes after switching off the transformer before beginning fur-
ther work on the protective relay so that the gases can dissipate.
► Ensure that there are no ignition sources such as naked flames, hot sur-
faces or sparks (e.g. caused by the build-up of static charge) in the imme-
diate surroundings and that none occur.
► De-energize all auxiliary circuits before beginning work.
► Do not operate any electrical devices during the work (e.g. risk of sparks
from impact wrench).
WARNING
Danger of death or severe injury!
Danger of severe injury or death if on-load tap-changer and transformer are
insufficiently tested.
► Be sure to contact Maschinenfabrik Reinhausen to check on-load tap-
changer and transformer if the protective relay has tripped.
► Only use the equipment again when you are sure there is no damage to
the on-load tap-changer or transformer.
When the circuit breakers have been tripped by the protective relay, proceed
as follows:
1. Establish time of tripping.
2. Determine operating position of on-load tap-changer.
3. As a precaution, block the motor-drive unit by tripping the motor protective
switch to prevent the on-load tap-changer from being actuated by remote
control.
4. Check the on-load tap-changer head cover. If insulating fluid is leaking,
close the oil conservator stop valve immediately.
5. Check whether the flap valve of the protective relay is in the OFF or OP-
ERATION position.
7.1.1 Flap valve in OPERATION position
If the flap valve is in the OPERATION position, there may be a fault in the
tripping circuit. Check the tripping circuit in this case. If you are not able to
clarify why the protective relay tripped, be sure to contact Maschinenfabrik
Reinhausen to check the on-load tap-changer.