2
STANDARD OPERATING INSTRUCTION GUIDE FOR LOW
‐
VOLTATE BREAKER & SIGNAL LIGHT
WARNING : ON SINGLE PHASE & THREE PHASE TRANSFORMERS
WITH THE SECONDARY CIRCUIT BREAKER OPEN, THERE MAY BE
SUFFICIENT COUPLING TO THE WINDING SO THAT PERCEPTIBLE
SHOCK MIGHT BE OBTAINED FROM THE SECONDARY TERMINALS.
A circuit breaker when provided is mounted inside the tank, under
the liquid level. The func on of this breaker is to open the low
‐
voltage circuit and protect the transformer from faults or severe
overloads. A red signal light, when provided, gives the warning that
the load has reached a value near the tripping point of the breaker.
The signal light remains lighted un l reset (turned o
ff
) by means of
the breaker
‐
opera ng handle. Transformers should not be operated
under load condi ons that will cauase the red light to appear
frequently, since it indicates an overload on the transformers. 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.
The circuit breaker opera ng handle and posi on indicator are
shown in Figure 1. Transformers are shipped with the circuit
breakers closed. To open the low voltage circuit manually, move the
handle so that the pointer moves from “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 insure that 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 the high voltage is disconnected.
To close the breaker a er manual opening move the handle so the
arrow points towards “C”. If the breaker has been tripped it is
necessary to move the arrow towards “R” to reset the breaker
before closing the breaker by moving the arrow towards “C”.
If a fault exists or and excessive load exists at the me the breaker is
closed, the breaker will reopen even though the opera ng handle is
held in the “C” (closed) posi on.
To reset the signal light, rotate the handle to the “L” (light), and then
return to “C” (close). If the light fails to go out, the transformer is s ll
over heated.
Provision is made for checking the signal light bulb when the
transformers is in service, to do this, rotate the handle to “L” (light)
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‐
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and the light should come on. If it does not, the bulb should be
replaced. The bulb is a standard six
‐
volt, GE bulb No. 44, and is
replaceable from outside the transformer and by removing the signal
light lens. A er checking return the opera on handle to “C”. Faulty
bulbs should be replaced, since opera ng the transformer with the
faulty bulb or without a bulb may result in radio noise.
Some circuit breakers are equipped with emergency overload
devices, which can be used to restore service following a circuit
breaker opera on due to overload. With the emergency lever in the
normal posi on the breaker will trip at its normal se ngs as
calibrated at the factory. Moving the lever in clockwise direc on (see
Figure 1) increases the se ng so that a higher temperature is
required to trip the breaker. 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 when it is
returned to the normal posi on a er emergency opera on.
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