Overtemperature Thermoswitch - Saft 4579 Component Maintenance Manual With Illustrated Parts List

COMPONENT MAINTENANCE MANUAL
Verify the ohmmeter indicates 7355Ω ±74Ω at 32°F ±3°F (0°C ±1.5°C).
(5)
(6) Following the low temperature test, slowly raise the temperature to 140°F
±5°F.
(7) Verify the ohmmeter indicates 560Ω ±12Ω at 140°F ±5°F.
NOTE:
(8) If the thermistor fails any of the above tests, replace the temperature sensor
assembly (22) with a factory new.
K.

Overtemperature Thermoswitch

The overtemperature thermoswitch is part of the Temperature Sensor Assembly (22).
It is mounted on the plate (23) in contact with the face of cell #4. Disassembly is
required in order to test the thermoswitch (DISASSEMBLY). Check the function of
the overtemperature thermoswitch as follows:
(1) Connect an ohmmeter to connector pins 8 and 9 of the temperature sensor
assembly (22). Ohmmeter should read >1MΩ (open thermoswitch contacts) at
room temperature [70°F (±5°F) (21.1°C (±2°C)].
(2) Suspend the thermoswitch plate (23) with thermoswitch in a beaker of water
with the thermoswitch a minimum of 2 inches from the bottom and 1 inch
from the top of the water surface.
(3) Insert a thermometer, or other suitable temperature-measuring device in the
water with the bulb adjacent to the thermoswitch.
(4) Slowly raise the water temperature to 150°F (65.55°C) while observing the
ohmmeter (still connected to pins 8 and 9). Ohmmeter should read >1MΩ at
temperatures below 150°F (65.55°C).
(5) Continue to raise the water temperature to 160°F (71.11°C) and allow the
temperature to stabilize at that temperature. The thermoswitch should close
(<1MΩ resistance) by the end of 5 minutes at a stabilized temperature of
160°F (71.11°C).
(6) Slowly add cool water to the beaker to reduce the water temperature to 135°F
(57.22°C). The thermoswitch should open (>1MΩ) within 5 minutes at a
stabilized temperature of 135°F (57.22°C).
SAFT AMERICA INC.
4579
At 160°F (71°C) the thermistor resistance shall be 382 ±74Ω.
24-31-05
PAGE 112
July 13/01