Bitzer SE-E4

What does Bitzer SE-E4 mean?

The SE-E4 is a BITZER compressor protection device for high motor voltages between 200 and 690 V. It monitors motor winding, discharge-gas and oil temperature and locks out immediately when a preset limit is exceeded. It adds phase monitoring (rotation direction, phase sequence and phase failure) plus broken-lead and cable-short monitoring, and complies with EN/UL 60730. It replaces the SE-E1 and SE-E3.

Symptoms

• Compressor stopped on over-temperature or a phase fault
• Trip shortly after start due to wrong rotation direction
• Safety chain opened by the protection relay
• Device locked and not restarting

Common causes

• Winding, discharge-gas or oil temperature over the limit
• Wrong rotation direction / phase sequence at start
• Phase failure (loss of a supply phase)
• Broken or shorted temperature-sensor cable

Diagnostic steps

1. 01

   Check the cause of the trip

   Determine whether a temperature limit, a phase fault or a sensor fault locked the device; it will not reset until corrected.

2. 02

   Verify phase rotation and supply

   Confirm correct rotation direction and that all phases are present, since the SE-E4 monitors rotation, phase sequence and phase failure.

3. 03

   Let the compressor cool

   Allow winding and oil temperatures to fall back into range if the trip was thermal.

4. 04

   Inspect the sensor cable

   Check the temperature-sensor wiring for breaks or shorts, both of which lock the device.

5. 05

   Unlock the device

   Interrupt the protection-device supply voltage for at least five seconds, then re-energize to clear the lockout.

When to call a professional

Only trained, authorized specialists may work on the compressor and system. Phase-rotation, phase-failure and high-voltage (200-690 V) faults involve live electrical work that should be handled by a qualified technician. Recurrent thermal lockouts indicate a motor or cooling problem needing professional diagnosis rather than repeated resets.