Figure 2-6. Temperature winding snap action auxiliary switch contacts and lead color code

Transformer (fig. 2-7).

(4) The winding temperature gage (2, fig. 2-

7) provides a means of reading an equivalent of the

(1) The liquid-level gage (1) is a magnetic

transformer winding hot-spot temperature. The gage is

gage to indicate the level of the insulating oil in the main

a standard type AWR. It consists of a thermometer with

transformer tank. The level will rise .50 inches for

(every 10C rise in temperature. The gage may be

two snap action switches mounted in a hermetically

sealed case. The switches permit the instrument to be

removed whenever the liquid is at or below the 25 Level

used to initiate an alarm in the event winding

temperatures become excessive. The dial is calibrated

(2) The pressure-vacuum gage (3) is of the

in degrees centigrade. A white pointer indicates the

compound type and is calibrated in psi. Gage reading

winding hotspot temperature. A red pointer shows the

should vary as the transformer temperature (changes

maximum temperature obtained since last reset. To

and should normally indicate a positive pressure. (The

reset the maximum reading (red) pointer remove the

gage is expected not to read accurately near the zero

magnet (5), that is attached to the gage by a chain, from

point). When the transformer is deenergized or is

its holder on side of case. Wipe magnet across face of

operating under light or no load conditions in low

dial counterclockwise, or toward zero. Replace magnet

ambient temperatures the gage may indicate a vacuum

in holder. For switch lead color code and contacts see

within the tank. A lack of any change in reading with

figure 2-6.

changes in temperature is an indication of a leak in the

transformer seal and should be investigated. See

nameplate (61 for maximum plus and minimum minus

readings.

(3) The liquid temperature gage (4, fig. 2-

7) is used to indicate the top liquid temperature of the

transformer. It is a standard type AL thermometer

mounted with its temperature sensitive bulb in a well.

The well extends into the transformer's top liquid and is

secured with a union nut. the well is liquid-tight thus

permitting removal of the thermometer without lowering

the liquid level or breaking the transformer seal. The

dial calibration is in degrees centigrade. A white pointer

indicates the liquid temperature. A red pointer shows

the maximum temperature attained since last reset. To

reset the maximum reading (red) pointer, remove the

Figure 2-6. Temperature winding snap action auxiliary

magnet (5), that is attached to the gage by a chain, from

switch contacts and lead color code.

its holder on side of case. Wipe magnet across face of

dial counterclockwise, or toward zero. Replace magnet

in holder.

2-11