Hussmann Ingersoll Rand User Manual page 210

Protection Device Models
SE-B1 is the typical motor protection module for IR compressor models up through IR4C2397.
Compressors larger than the IR4C2397 use a module SE-B2. For compressor models IR4C0770 through
IR4C2397 utilizing the PTC temperature sensor for oil control, the protection module used is the model
INT69/70.
Function
These protection devices monitor motor temperatures by means of PTC-sensors that are located in the
motor windings. In addition to monitoring motor winding temperatures, for models IR4C0770 through
IR4C2397, the INT69/70 module also monitors oil level using a PTC sensor mounted in the front
bearing cover.
Motor Winding Temperature Protection (SE-B1, SE-B2, INT69/70):
1) An increase in motor winding temp will increase the resistance measured by the PTC sensors
embedded in the windings. When the resistance reaches 4.50 kΩ, the module will lockout the
control circuit.
2) The module will not reset until the PTC resistance reaches 2.75 kΩ (+/- 20%).
3) The module must be manually reset by interrupting the power supply to the module.
4) To test the integrity of the module's reaction to excessive motor winding temp:
A) Disconnect the power supply to the module.
B) Locate the compressor's sensor terminals (M1 & M2) and remove one of the leads (remove
the green wire if testing the INT69/70).
C) Energize the module (restore power)
D) If the module is operating properly, contacts #11 & #14 will open (dropping out the control
circuit) and contacts #11 & #12 will close. This will lockout the compressor's control circuit
and the COT light will come on. Contacts #11, #12 & #14 are located on the module.
INT 69/70 - Sequence Of Operation (Oil Level Sensor):
1) When the oil level in the bearing cup falls to a level where it no longer covers the PTC sensor, the
heater will cause the resistance measured by the PTC to increase. If the resistance reaches 4.50 kΩ
(+/- 20%), the INT will open contacts #11 & #14 and the contacts between #11 & #12 will close.
At the same time, contacts #24 & #21 (located on the INT69/70) will close, energizing the Oil Fail
Relay. Therefore, when an INT69/70 is locked out because of "low oil level", the "COT" light &
the "Oil Fail Relay" light will be on.
2) Under normal operating conditions (adequate oil level) the resistance of the PTC will be 2.2 kΩ
(+/- 5%).
Electrical Data
Motor Protection Devices
10