periodic inspection required by Section 8 of this instruc
tion book. If shipped separately or if the body is replaced,
check operation of the float over its entire range to see
that it is free and that the needle follows movement of the
float. Coat the gasket on both sides and edges with gasket
cement (53351
GH).
Allow to dry 15 minutes. Apply a
second coat of cement, wipe off excess from the edges
and put gasket in place. Mount the instrument body and
tighten the bolts securely to insure against oil leaks. If
alarm contacts are used, make proper connections to the
control box.
Table 2 - Liquid Temperature Gauge
Average
Correct Filling Level
Liquid
(Percent of Scale Above
Temp. (0C)
or Below 25°C Level)
85 (high)
100
70
75
55
50
4
0
25
25 (Normal)
0
10
-33
-5
-67
-20 (Low)
-100
5 .5 Liquid Temperature Gauge
The temperature gauge is furnished to indicate the top
liquid temperature in the tank. The temperature sensitive
element is mounted in a leak-proof well, permitting re
moval of the thermometer without lowering the liquid
level. The device is furnished with a red pointer to show
the highest temperature attained since last reset. To reset
the maximum indicator, rotate the magnet at center of
the dial. On other designs, remove the attached magnet
and wipe across the face of the dial.
During normal operation the liquid temperature gauge
should read less than the sum of the ambient temperature
and the rated temperature rise. For example, 30°C am
bient
+
55°C rated temperature rise
=
85°C top oil tem
perature.
CAUTION
Do not fill the well with solid or liquid before inserting
the stem of the thermometer since this may damage the
instrument without appreciably helping the transfer of
heat from the oil to the sensitive element. The thermom
eter should not be tightened in the well any more than is
necessary to place the dial in an upright position.
Fig.
3
Front and Side View of Indicator with Alarm
Contacts
7
The thermometer can be furnished with a Single pole
single throw contact for fan starting and a Single pole
double throw contact for high temperature alarm.
The contact settings are normally 60°C with adjust
ments of ±10 degrees for contact number 1, and 90°C
with adjustment of
+
10, and -25 degrees for alarm con
tact number 2. Alarm switch ratings are in Table 1, page
4.
The instrument is shipped fixed to the tank wall so
that no installation is required. Maintenance is not re
quired except for the periodic inspection required by Sec
tion 8 of this instruction book.
5 .6 Pressure-Vacuum Gauge
The pressure-vacuum gauge indicates whether the gas
space in the tank is under positive or negative pressure.
The pressure will vary depending on barometric pressure
and the liquid temperature, and it should normally be
slightly positive. If the transformer is de-energized or op
erating un
d
e
r light load
in
low
ambients, the pressure
may go negative.
CAUTION
If the pressure-vacuum gauge reads zero and does not
change under any transformer load, the transformer
should be checked for a possible leak. A leak will allow
moisture, which will damage the insulation, to enter the
transformer. Transformer life will be reduced if leaks are
not repaired.
The gauge may be furnished with a pressure-vacuum
switch with two Single pole double throw contacts for re
mote alarm on large positive or negative gauge pressure.
Alarm switch ratings are in Table 1, page
4.
The switch
contacts are set to trip at 3.5 psi vacuum and 7.0 psi pres
sure. Ignoring an alarm may cause permanent bending or