Troubleshoot a control relay by checking resistance or continuity
Troubleshoot a control relay by switching the contacts (lift the flap)
Troubleshoot a control relay by checking resistance for the rear contacts
Common Component Failure Problems
These relays may be called either cube relays or control relays. These relays may also be either double-pole double-throw or single-pole single-throw.
Double-Pole Double-Throw (DPDT)
- Relay is not working properly.
- Check voltage is coming into terminal A1. (May also be called terminal 2.)
- Confirm wiring from terminal A2 (may also be called terminal 7) to neutral.
- Lockout, tagout
- Check resistance of the control relay coil.
- Check terminal A1 to terminal A2.
- Good reading should be around 470 ohms.
- OL reading indicates coil has burnt out and the relay needs to be replaced.
- A low ohm reading indicates a lack of proper resistance. May result in overcurrent in the system and a tripped overload or blown fuse.
- Check continuity of the contacts.
- Measure across the contacts.
- Manually trip the relay by using the flap. (The indicator should turn orange.)
- NC contacts (1 to 4 and 8 to 5) should have continuity until flap is manually tripped.
- NO contacts (1 to 3 and 8 to 6) should have continuity after the flap is manually tripped.
- Bad contacts will not change state regardless of the position of the test flap.
- If terminals or contacts are reading continuity when they shouldn't or not reading continuity when they should, connections have failed either open or closed.
Single-Pole Single-Throw (SPST)
Troubleshooting this type of relay is similar to troubleshooting the DPDT relay, just with fewer contacts.
- Relay is not working properly.
- Check voltage is coming into terminal A1.
- Confirm wiring from terminal A2 to neutral.
- Lockout, tagout
- Check resistance of the control relay coil.
- Check terminal A1 to terminal A2.
- Good reading should be around 450 ohms.
- OL reading indicates coil has burnt out and the relay needs to be replaced.
- An ohm reading below 450 ohms indicates relay is going bad. May result in overcurrent in the system and a tripped overload or blown fuse.
- Check continuity of the contacts.
- Measure across the contacts.
- Manually trip the relay by using the flap. (The indicator should turn orange.)
- NC (1 to 4) contacts should have continuity until flap is manually tripped.
- NO (1 to 3) contacts should have continuity after the flap is manually tripped.
- Bad contacts will not change state regardless of the position of the test flap.
- If terminals or contacts are reading continuity when they shouldn't or not reading continuity when they should, connections have failed either open or closed.
Troubleshooting Instrumentation/Tools
Troubleshooting Step-by-Step Example
Double-Pole Double-Throw (DPDT) Control Relay
Single-Pole Double-Throw (SPDT) Control Relay
Additional Troubleshooting Information
Related Parts:
How Control/Cube Relays Work:
Schematic:
Where to Purchase:
1-Pole Control Relay - Automation Direct
2-Pole Control Relay - Automation Direct
Unless specified otherwise, any and all work on this page is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.