Three of the sensors are thermistor probes that monitor the temperature of the 4-Wire transformer. These sensors report the information to the General Purpose Interface Board. The General Purpose Interface Board reports general temperature monitoring information to the APC2 Board.
Three of the sensors are thermal switches that close when the temperature of the 4-Wire Transformer reaches 150 °C (302 °F). These switches are read by the 4-Wire Thermal Switch monitor located on the fan plenum shield, which lights the yellow warning LED on the front door of the cabinet.
Three of the sensors are thermal switches that close when the temperature of the 4-Wire Transformer reaches 160 °C (320 °F). These switches are read by the 4-Wire Thermal Switch monitor that is located on the fan plenum shield. The 4-Wire Thermal Switch monitor sends an Emergency Power Off request to the UPS system.
Note: The thermistor monitors the transformer temperature in the Phase A and Phase C coils only.
 | |
| Illustration 1 | g01271808 |
4-Wire Transformer (Top View) (1) Terminal Block (Temp Warning) (2) Terminal Block (Temp Shut Off) (3) Terminal Block (Thermistor Probe) | |
 | |
| Illustration 2 | g01271810 |
Access to the top of the 4-Wire Transformer (Version 1 Hardware) | |
 | |
| Illustration 3 | g01271812 |
Access to the top of the 4-Wire Transformer (Version 2 Hardware) | |
Removal
- Refer to the information in the Systems Operation, Testing and Adjusting, "Internal Component Preremoval Steps (4 Wire Transformer Cabinet)"in order to de-energize the system and gain access to internal components.
- Unscrew the sensor from the wire terminal.
Refer to Illustration 4.
 | |
| Illustration 4 | g01271813 |
4-Wire Transformer Sensor Wire Connections (1) Terminal Block (Temp Warning) (2) Terminal Block (Temp Shut Off) (3) Terminal Block (Thermistor Probe) | |
- Remove the sensor by pulling it from the appropriate transformer coil. Make note of the location from where the sensor is removed.
Installation
- Insert the sensor into the appropriate transformer coil location.
| | |
| Illustration 5 | g01271813 |
4-Wire Transformer Sensor Wire Connections (1) Terminal Block (Temp Warning) (2) Terminal Block (Temp Shut Off) (3) Terminal Block (Thermistor Probe) | |
- Attach the sensor leads to the wire terminal.
Refer to Illustration 5.