Relay Chattering: Causes & Prevention

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In summary, relay chattering is often caused by pressure fluctuations or insufficiently sourced system power supply. To prevent it, one can decouple the coil drive from the relay load, increase head room on the power supply, or use separate power for the coil and load. Another common cause is oscillation on the coil independent of the load.
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kal22
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What causes relay chattering and what can be done to prevent it?
 
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  • #2
What are your thoughts? What specific circuit are you working with? Is this homework?
 
  • #3
I've dealt with a relay chattering on an A/C unit due to the pressure fluctuations of the reciprocating compressor on the pressure switch that pulled-in the relay...

...so this is very situation specific.
 
  • #4
How is 'chattering' defined? I mean, as in frequency and/or mechanical vibration. If it's really fast, like a buzzer, I'm wondering about a bad connection that causes the primary circuit to fail when the armature moves...?
 
  • #5
Two common reasons:
1. When the relay 'makes' the new system load causes a step current drop in the relay drive coil due to an insufficiently sourced system power supply. This causes the relay to 'break', the open load allows the coil current to recover closing the relay again an so on. Decouple the coil drive from the relay load to correct: more head room on your system power supply, separate power for coil and load (usually is anyway for a relay - that's the point) or better local AC coupling caps (careful - can be complicated as you can just create more problems in a tank circuit w/ the coil and caps)
2. A simple oscillation of some kind on the coil (signal side) independent of the load.
 

FAQ: Relay Chattering: Causes & Prevention

What is relay chattering?

Relay chattering is a phenomenon that occurs when a relay switch rapidly opens and closes due to a weak or unstable electrical signal. This can result in multiple on-off cycles, potentially causing damage to the relay or connected devices.

What are the causes of relay chattering?

The most common cause of relay chattering is a weak or unstable electrical signal, such as a low voltage or fluctuating power supply. Other possible causes include mechanical issues with the relay, such as worn out contacts or improper installation, and electromagnetic interference.

What are the effects of relay chattering?

Relay chattering can have several negative effects, including damage to the relay and connected devices, as well as increased energy consumption. It can also cause system malfunctions and disruptions, leading to potential safety hazards or financial losses.

How can relay chattering be prevented?

To prevent relay chattering, it is important to identify and address the root cause. This may involve using a stable power supply, ensuring proper installation and maintenance of the relay, and implementing measures to reduce electromagnetic interference. Using surge protectors and noise filters can also help prevent relay chattering.

What are some common techniques for mitigating relay chattering?

Some common techniques for mitigating relay chattering include using snubber circuits, which can reduce voltage spikes and noise, and implementing software filters to stabilize the electrical signal. Additionally, selecting high-quality relays and regularly inspecting and maintaining them can help prevent relay chattering.

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