How do I know if a compressor's asset controller has TRIAC outputs?
Why is this question important?
You need to know whether the asset controller uses TRIAC outputs in order to select the correct Status Detection Connection method during installation of the Link+ or Drive+ systems.
- See Link+ Installation Guide – page 5
- See Drive+ Installation Guide – page 6
Choosing the wrong connection method can result in incorrect status readings, which affects monitoring and system reliability. Identifying the type of output (TRIAC or relay) ensures a proper and stable installation.
What is a TRIAC output?
A TRIAC (Triode for Alternating Current) is a solid-state switch used in some older asset controllers. When turned OFF, TRIACs still leak a small current—usually several milliamps—causing a low voltage across connected devices (like motor contactors), even when they are de-energised. This can trick digital inputs, (such as a Link+ or Drive+ module), into reading the output as ON when it's actually OFF.
How can I identify if an asset controller has TRIAC outputs?
Age Rule of Thumb: If the controller is more than 20 years old, suspect it uses TRIAC outputs. Most newer controllers (especially European-built) use mechanical relay outputs. TRIACs may still appear in non-European compressors or PLC-controlled systems.
How do I test for TRIAC outputs?
- Ensure the compressor is in a stopped condition with no faults.
- Set your multimeter to AC voltage mode.
- Measure the voltage across A1 and A2 terminals of the compressor’s main motor 'Line' contactor.
Interpreting the result:
- > 6 Vac when OFF (typically ~⅓ of full ON voltage): Likely a TRIAC output.
- Near 0 Vac when OFF: Likely a relay output.
What should I do if TRIAC outputs are present?
Use “Status Detection Connects – Option B” in the Drive+ & Link+ Installation Guide to handle the signal correctly. Following the correct option ensures reliable status detection and avoids false readings.
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