Sticky Relays on 32-Relay ProXR Boards?

Hardware
1

I’m working with several 32-relay ProXR boards. I tested each relay to ensure proper functioning using the NCD Base software, but I observed that a few relays take time to turn ON when commanded.

My setup:
• Software: NCD Base Station 4.0.8
• Power supply: 12V w/ current limit 1A
• Primary board PN: PR60-72 ZADSR32xDPDT REV.G2B
• Expansion board PN: PR60-54 XR32xDPDT REV.G2C
• Relays PN: AXICOM V23105A5003A201

Here’s a list of things I’ve observed:
1. When the faulty relays are commanded to switch ON, they take upwards of 30-60s to actually switch ON. Tapping them with a pen will sometimes makes them switch ON immediately.
2. When the faulty relays are commanded to switch OFF, they switch OFF immediately.
3. If I leave the faulty relays ON, momentarily switch them off, then back ON, the time they take to switch ON is lower than if I had left them OFF for longer.
4. The faulty relays pull the same amount of current as the functioning relays.
5. The voltage across the faulty relays is the same as the voltage across the non-faulty relays (~11.90V)

This behavior is the same regardless of whether I address the relays individually through the software or if I address their bank. These observations seem to point to a mechanical problem with the relays. Is this a known issue?

Any help would be greatly appreciated.

2

Hi,

Does this seem to be an issue with a particular bank (1-8, 9-16, etc.) or is it individual relays throughout the board?

Is this issue occurring on both the master and expansion board?

If there is a load, what is being switched by the relay? It it an inductive load? Does this issue occur if no load is connected?

If there is a load, what contacts are you wiring the load to (C to NO, C to NC)?

Are there multiple relays activated (coil powered) when this issue occurs? Does this issue occur if all other relays are off?

What communication interface is being used?

3

Across the ten master-expansion pairs I tested, I saw five faulty relays. It seems to be an issue with the individual relays, not the banks, because some of the failures happen within banks, some happen across banks, and some happen across master/expansion.

Faulty Master-Expansion A
Master, Bank 2, Segment 5-8:

  • Was not able to identify the failing relay before it unstuck itself. Its somewhere in this bank.

Master, Bank 4, Segment 5-8:

  • K32 is stuck

Faulty Master-Expansion B
Master, Bank 2, Segment 1-4:

  • K12 is stuck

Expansion, Bank 1, Segment 5-8:

  • K5 is stuck
  • K6 is stuck

No loads have ever been connected to these boards. I’m testing continuity across the relay contacts using a multimeter.

I have tested the faulty relays by having them be commanded ON individually, as well as having the entire bank they belong to be commanded ON. In both cases the faulty relays fail to switch ON immediately. The other relays work fine.

My data link is: USB → DFRobot Multiplexer V3.0 → NCD.io RS485 MBUS → Master board. NCD Base station is configured for 9600 baud.

4

Unfortunately relay failures like this aren’t something seen very often out of the box. Usually what would cause something like this is a high power load causing damage to the coil arm/contacts or a power event on the 12VDC coil side of the relay damaging the electro magnet in the relay or the relay driver chip.

I’d have to recommend an RMA for us to look at it and repair/replace as needed. You can request an RMA at: Log In ‹ NCD.io — WordPress