Howard Medium Power Substation - Manual (Page 19)

Medium Power Substation Transformers
Document 2.4.06, Revision 4
June 2013
On-load Tap Changer
Some transformers are provided with an on-load tap
changer that can change taps while under load, thereby
regulating the output voltage. A user-programmable
control unit automatically operates the on-load tap
changer to maintain the selected output voltage. Refer
to the manual provided with the on-load tap changer for
warnings and for operating and maintenance
instructions.
High-voltage Bushings
Transformers are normally supplied with draw-lead
or condenser type high-voltage bushings. If bushings
were removed for shipment, install draw-lead bushings
according to instructions found on Pages 12 and 13,
and install condenser-type bushings according to
instructions furnished with the transformer.
WARNINg : DO NOT EXCEED THE CANTIlEvER
lOAD RATING OF THE BUSHING. GREATER
lOADS MAY CAUSE BUSHING DAMAGE THAT COUlD
RESUlT IN SEvERE PERSONAl INJURY, DEATH, OR
PROPERTY DAMAGE.
Draw-lead bushings usually require no maintenance
except as described on Page 20. Maintenance
instructions for condenser-type bushings are furnished
with the bushings.
low-voltage Bushings
Transformers are normally supplied with cast resin or
porcelain draw-lead bushings. These bushings usually
require no maintenance except as recommended on
Page 20.
Surge Arresters
Transformers may be furnished with optional distribution
class, intermediate class, or station class surge
arresters. Arresters are shipped separately from the
transformer to prevent damage. Upon delivery, unpack
the arresters and carefully inspect them for damage,
especially the porcelain components. Install surge
arresters according to instruction found on Page 14.
19
Radiators
Transformers are furnished with radiator assemblies
(usually panel type) to dissipate heat from the
transformer. Cooling fans may also be furnished to
provide additional loading capability without overheating
the transformer. Radiator assemblies may be shipped
separately from the transformer to reduce the shipping
size of the transformer and to prevent damage. When
radiators are shipped unattached, they should be
installed in the field according to the instructions on
Pages 11 and 12.