COMEM Buchholz Relays Manual De Instrucciones página 5

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Figure A
G
The recommended angle of inclination of the Buchholz
relay pipework should be between 0 to 5 degrees.
The pipe from the transformer to the Buchholz relay must
exit the transformer at the highest point, it must be strai-
H
ght and the recommended length to the relay should be 10
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times the internal diameter of the pipe (L1). The distance
between the Buchholz relay and the conservator should be
at least 3 times the internal diameter of the pipe (L2).
Make sure that:
• Buchholz relay must initially be full of oil which means
that the minimum oil level of the conservator must be
higher than the discharge valve on the top of the relay
(Fig. A/3).
• Gases produced in the insulating liquid can flow
unimpeded to the Buchholz relay.
• The red arrow on the Buchholz relay points to the
conservator.
• The flanges are stressed evenly when tightening the
screws.
• The slope of the pipe to the conservator is between 0°
and 5°.
• The position of the Buchholz relay in relation to the
direction of flow does not deviate from the perpendicular
by more than 5°.
• The pipe has no elbows, and bends are designed
preferably with an inside pipe radius R > 100 mm.
• The free pipe length between the Buchholz relay and the
tank should be at least 10 times the internal diameter
• The free pipe length between the Buchholz relay and the oil
conservator should be at least 3 times the internal diameter
(Should the distance exceed the above values, a support
has to be provided in the immediate vicinity of the
Buchholz relay ).
CAUTION
Make sure during installation that no dirt, moisture or foreign
matters get into the relay.
The insulating liquid of the transformer/reactor may not contain
conductive materials!
After the installation check the function of the relay.
The contacts (alarm and trip) can be tested manually
moving the rod (mechanical test).
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Mechanical test
Unscrew the cap nut (Fig.B/1) then push the button
CREATED BY
Diego Boro
(Fig.B/2) following the red arrow direction (figure B). In
APPROVED ON
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RESPONSIBLE COMPANY
COMEM
this way the floats will be moved down and alarm/trip
RESPONSIBLE DEPARTMENT
ITABB-9AAE306693
switches will commutate (the sequence can be alarm/trip
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together or alarm before trip). After having been quickly
released (do not accompany it), the button automatically
comes back to original position. Once the verification has
been completed, fit and tighten the cap nut. This test does
not give the conformity of the electrical scheme.
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Figure B
Damper Held functioning
In case of Buchholz Relay equipped with feature "damper
held" (option), the trip signal generated by the flow vane is
kept on the triggered position even after the reduction of
oil flow. This means that, in order to reset the trip signal,
it is necessary to push down the mechanical test button
(Fig.B/2)
For Buchholz relays with damper held functioning the trip signal
(generated by the flow vane) shall be unlocked by pushing the
mechanical test button (Fig.B/2)
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DRAWING SHEET ISO 5457:1999-A2T
CAUTION
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