ERMCO 11-16-21 User manual

1
INSTRUCTION
MANUAL #105
THREE PHASE POLE MOUNTED DISTRIBUTION TRANSFORMER
ERMCO | 2225 Industrial Road | Dyersburg, TN 38024 | (800)238‐5587
INTRODUCTION
This instrucon manual provides general informaon for the
installaon, operaon, and maintenance of ERMCO three‐phase, pole
mounted transformers. These transformers are to be applied and used
per the “usual service condions” describes in IEEE C57.12.00 (General
Requirements for Liquid‐Immersed Distribuon, Power and Regulaon
Transformers).
RECEIVING AND INSPECTION
ERMCO pole transformers are shipped filled with insulang
transformer oil. Immediately upon receipt, and before being put in
service, transformers should be inspected for any external damage or
loose parts caused by shipping and handling. Damage presumed to
have occurred during shipment should be noted, and your ERMCO
sales representave contacted.
Extreme care is taken at the factory in the processing and sealing of
the transformer to insure that it is clean and dry, and of adequate
dielectric strength. Normally, therefore, it is not recommended that
the transformer seals be broken for internal inspecon. If it is decided,
nevertheless, that the transformer be opened, adequate precauons
should be taken as outlined elsewhere in these instrucons.
HANDLING AND INSTALLATION
Transformers should be lied by the liing lugs only. The transformer
bushings should not be used for liing or moving the transformer into
posion. The transformer should be kept upright at all mes and not
pped over on its side for any reason. This will prevent air bubbles
from entering the coil which could degrade the dielectric strength.
Support lugs for direct pole mounng are provided in accordance with
IEEE standards. Hangers and kickers for cross arm mounng is to be
provided by the user. When installed, transformers should be
protected from dangerous overloads, over voltages and lightning by
suitable, approved devices.
OIL
Transformers are thoroughly dried at the factory and filled with
ERMCO inhibited mineral oil having a minimum dielectric strength of
30 kV at 60 Hz when tested per ASTM D‐877. ERMCO inhibited mineral
oil contains less than 1 ppm of PCB's at me of manufacture. The
transformer should never be energized unless it is filled with oil.
If it should be found necessary to add to or replace the oil in the
transformer, only clean dry oil having the minimum dielectric strength
of 30 kV and less than 1 ppm PCB's should be used. Before opening
the transformer, sufficient me should be allowed for the transformer
to come to temperature equilibrium with the air in the room to
eliminate the possibility of moisture condensaon from the air.
A recommended procedure for opening the transformer is to first
bring the interior of the transformer to atmospheric pressure by
venng the automac pressure relief valve furnished on all ERMCO
transformers. The cover may then be removed. Natural rubber hose
should not be used in the transfer of oil. The correct oil level at 25°C is
marked on the inside of the tank.
Care should be taken to re‐seal the transformer so that moisture is
permanently excluded from the interior. A pressure test using dry air
or nitrogen, may conveniently be made through the pressure‐vacuum
fing, aer removing the pressure relief valve, to be sure all seals are
ght. Pressurize the transformer to 5 psig and hold for 30 minutes. A
drop in pressure during this me would indicate the transformer is not
properly sealed and the tank and fings should be checked and the
leak repaired. Finally, the pressure relief valve should be installed and
carefully ghtened.
CONNECTIONS
Refer to the transformer nameplate for the kVA rang and the
permissible connecons. No connecons other than those shown on
the nameplate should be made; and none of the connecons should
be changed while voltage is applied to the transformer. Provision is
made for grounding the tank by means of a tapped pad or ground
connector.
OVERLOAD AND OVERVOLTAGE PROTECTION
Transformer protecon against overloads and over voltages may be
obtained by suitable devices applied in the field to convenonal
transformers, or by use of protected transformers (ERMCO CSP or CP
types) as supplied from the factory.
1. Fuses: High voltage fused cutouts are recommended for
protecon of convenonal transformers against overloads and to
protect the line against outages. On ERMCO CSP and CP
transformers, a fusible protecve link, mounted inside the tank,
is provided in series with each HV terminal. In case of internal
failure of the transformer, the protecve link disconnects the
transformer from the line without affecng line fuses or breakers.
When the available fault current exceeds the maximum
interrupng rang of the protecve link, a current liming fuse
should be used in series with the protecve link.

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THREE PHASE POLE MOUNTED DISTRIBUTION TRANSFORMER INSTRUCTION
MANUAL #105
2. Lightning Arresters: Convenonal transformers should be
protected by properly rated lightning arresters. Ground
connecons on the arresters should be made before connecon
to the high voltage line is made.
CSP transformers are lightning protected by gapped or direct
connected lightning arresters bolted to mounng pads welded to
the tank wall. Gapped arresters have an adjustable electrode on
the top terminal of the arrester to obtain the proper gap seng
to the bushing electrode.
Before the transformer is put into service, the gap type arrester
electrode should be checked for proper gap alignment and
spacing. Adjustments should be made as necessary.
3. Secondary Breakers: ERMCO CSP and CP transformers are
protected against secondary overloads and short circuits by an
internally mounted circuit breaker. The funcon of the breaker is
to open the low voltage circuit and protect the transformer from
faults or severe overloads.
The breaker operang mechanism is designed to be operated by
a lineman's hot sck. Transformers are shipped with the circuit
breakers closed.
To open the low voltage manually, move the handle fully
counterclockwise so that the pointer moves from the "C" (closed)
to "O" (open), at which point the circuit is open. Verify that the
circuit breaker is latched in the "open" posion. To ensure the
discharge of the stac charge which is somemes present in the
low voltage winding due to capacitance, it is recommended that
the low voltage be grounded aer opening the circuit breaker
unl aer the high voltage is disconnected.
To close the breaker, rotate the handle fully counterclockwise to
"R" (reset), which engages the latch mechanism, and then
clockwise to "C" (closed). If a fault exists or an excessive load
exists at the me the breaker is closed, the breaker will reopen
even though the handle is held in the "C" (closed) posion.
Some breakers are provided with a red signal light which gives
warning that the load has reached a value near the tripping point
of the breaker. The signal light remains lighted unl reset (turned
off) by means of the breaker operang handle. Transformers
should not be operated under load condions that will cause the
red light to appear frequently, since it indicates an overload on
the transformer. When such a condion exists, it is
recommended that a larger transformer be substuted to avoid
impairing the life of the smaller unit.
To reset the signal light without disconnecng the load, rotate
the handle to "L" (light), and then return to "C" (closed). If the
light fails to go out, the transformer is sll overheated. To check
the signal light bulb when the transformer is in service, rotate the
handle to "L" (light). The light should turn on. If it does not, the
bulb should be replaced.
Some circuit breakers are equipped with an emergency overload
device which can be used to restore service following a circuit
breaker operaon due to overload. The emergency overload
lever is located immediately above the breaker operang handle.
With the emergency lever in the normal posion, the breaker will
trip at its normal seng as calibrated at the factory. Moving the
lever in a clockwise direcon increases the seng so a higher
temperature is required to trip the breaker. The emergency
seng may be adjusted to an intermediate or extreme value.
This emergency seng provides extra load capacity and sll
permits manual breaker operaon, and also retains short circuit
protecon of the transformer. It is important that the emergency
seng be used only when, and as long as, absolutely necessary
because its use will result in a reducon of transformer life.
A meter seal is provided on the emergency lever to prevent
tampering. It is recommended that a new seal be applied to the
lever when it is returned to the normal posion aer emergency
operaon.
The breaker is a thermal and short circuit protecve device for
the transformer. It is not recommended that the breaker be used
for roune disconnect operaons.
GASKETS
Cover and bushing gaskets are all made of Buna‐N Nitrile rubber.
Gaskets may be reused if not damaged. Round covers must seat
evenly on the gaskets so that pressure is distributed evenly. The cover
must be ghtened firmly to insure an effecve seal.
DUAL VOLTAGE AND TAPS
ERMCO transformers rated for more than one primary voltage are
equipped with a dual voltage switch or tap changer. These switches
are externally operated, but should never be operated while the
transformer is energized. When switching from one voltage to
another, make sure the switch is in the proper posion before re‐
energizing the transformer. Aer turning the switch, ghten the
locking device to minimize the possibility of unintenonal
movement.
STORAGE
Transformers should be stored filled with oil and in a clean dry place,
if possible where there will be no extreme temperature changes.
Before the transformer is put in service, it should be checked in the
same manner as when received.
ERMCO | 2225 Industrial Road | Dyersburg, TN 38024 | (800)238‐5587

3
THREE PHASE POLE MOUNTED DISTRIBUTION TRANSFORMER INSTRUCTION
MANUAL #105
MAINTENANCE
A periodic visual inspecon of the transformer is recommended. At
such mes, the general condion of the following should be noted:
1. High voltage bushings
2. Low voltage bushings
3. Arresters (if provided)
4. Evidence of oil leakage
5. Ground connecons
6. Accessories
7. Safety labels.
Where tanks show evidence of rusng or deterioraon of the finish,
they may be cleaned and then retouched with paint. It is necessary to
remove all loose paint and rust by wire brushing, scraping, or sanding,
and clean with a good solvent. Apply an acrylic lacquer, alkyd enamel,
two part urethane or silicone alkyd primer, allow to dry, and then
apply a color matched compable top coat and allow to dry.
If metal is rusted to the point of being weak such that the tank
integrity can be compromised, repair or replace the part rather than
painng it.
REPLACEMENT PARTS
Replacement parts are available from ERMCO. When ordering parts,
give a complete descripon of the part. Also, give the kVA, voltage,
and serial number of the transformer, all of which may be found on
the nameplate.
ADDITIONAL INFORMATION
Complete informaon on details of construcon, installaon,
operaon and maintenance can be obtained from the ERMCO factory
or your nearest ERMCO Sales office.
ERMCO | 2225 Industrial Road | Dyersburg, TN 38024 | (800)238‐5587