How to determine if the relay is damaged

In the present world of industrial and household gadgets, relays play a vital role. If anything goes wrong with the relay, apart from disrupting the operation of the equipment, it may also lead to some serious safety hazards and further incur high maintenance costs. Now, how to identify whether the relay is damaged? This article helps in identifying the defective relays quickly from three major aspects: common symptoms, causes, and testing methods.

1. What is a relay? How does it work?

Relays are one of the more important electrical switches using a small current to keep control over large currents in modern circuit systems. It controls the turn-on or turn-off of the output terminal through electromagnetic or electronic principles for input signals. They can achieve the purposes of automation control, circuit protection, and signal transmission, and are widely used in industrial equipment, household appliances, and transportation systems.

Basic working principle of relay

The working principle of relays varies depending on their types, but they are generally divided into two categories: electromechanical relays and solid-state relays.

Electromechanical relay

1. Coil drive: When a small current passes through the coil of the relay, the coil generates electromagnetic force.
2. Contact action: Electromagnetic force pushes the contact to open and close, thereby controlling the on/off of high current.
3. Typical features: Electromechanical relays complete switch operations through mechanical actions, with a noticeable sound ("click" sound).

Solid state relay (SSR)

1. No mechanical components: switching is achieved through semiconductor components such as thyristors and optocouplers.
2. Fast switching: Faster than electromechanical relays, suitable for high-frequency operation.
3. Wear free: Solid state relays are more durable because they have no mechanical contacts.

Common causes of relay failures

The main reasons for the failure of relays normally include:

• Electrical overload: Exceeding the rated current or voltage of the relay can cause internal components to burn out.

• Mechanical wear: The contacts of classic electromechanical relays degrade with increasing usage.

• Poor installation: the failure to wire correctly or dissipate heat properly can cost the relay its performance.

• Environmental factors include dust, moisture, or extreme temperatures that can reduce the service life of relays.

If you want to choose relays that can adapt to complex environments, then welcome to check out our solid-state relay products.

Common symptoms of damaged relays

 

Overheated
If the relay is exposed to high temperatures for a long time, the insulation of the coil will decrease, leading to malfunction.

Mechanical wear and tear
Due to repeated switching, the contacts of the relay will wear or sink over time, leading to malfunctions.

 

Corrosion
If the relay is exposed to moisture or corrosive substances, the contacts and other components of the relay may corrode, leading to malfunctions.

Voltage spike
Voltage spikes or surges may occur in the circuit, causing relay contacts to melt and resulting in malfunctions.

Contaminated
If dirt, dust, or other pollutants enter the relay, it may cause the contacts to get stuck or damaged, leading to malfunction.

Coil burnt out
If the coil of the relay is exposed to excessive current or voltage, it may overheat and burn out, leading to malfunction.

How to test if the relay is damaged?

Here are three common relay testing methods:

Visual inspection
Check for burnt marks, corrosion, or physical damage on the relay housing.
Check for signs of dents or wear on the contacts.

Multi meter testing
Set the multimeter to resistance mode.
Test coil resistance: Damaged relays typically display open circuit or abnormal readings.
When activating the relay, check if the output terminal is connected.

functional testing
Connect the relay to the test circuit and observe if it switches properly.
If the relay cannot switch, it may indicate a fault.

• To help you better understand, let me give you an example：We use car relays, first connecting control circuits 85 and 86 with batteries. If you hear a clicking sound, it means the relay is working properly. And when we use a multimeter to test the control circuit, it shows a normal value between 50 and 200 ohms.If you are still unsure, we have provided a video below,

Time Segments for Testing Relays in the Video

Here are the key time segments in the video where relay testing is explained:

• 03:46 - How to Test Relays: An introduction to the basic steps for relay testing.
• 04:19 - Click Test: Demonstrates using a battery to power the control circuit and checking for a "click" sound.
• 05:32 - Resistance Test: Measures the resistance of the control circuit to ensure it falls within the normal range.
• 06:23 - Functional Test: Activates the relay to confirm the load circuit closes as expected.
• 07:09 - Replacement Testing Tip: Recommends swapping with a similar relay to see if it resolves the issue.

Click the links above to jump directly to the respective sections for a detailed demonstration. 

Preventive measures against relay failure

In order to extend the service life of the relay and prevent accidents, the following preventive measures can be taken to avoid relay failure:

• Matched specifications: use a relay with sufficient level against circuit requirements.

• Correct installation: Ensure wiring is proper and heat generation is sufficiently dissipated.

• Maintenance routine: Conduct routine inspections for wear or damage to relays.

• Upgrade to power relay: Power relays are more durable and resistant to wear.

• For more reliable relay products, please refer to our catalog for power relays.

When do I need to replace the relay?

The following situations indicate the need to replace the relay:

• The coil or contact shows obvious signs of damage

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• The test shows that the relay has no connectivity or abnormal switching.

• Relays frequently overheat or make abnormal noises.

• Under normal conditions, the load demand cannot be met.

• Timely replacement of faulty relays can prevent further damage to the system. Choose QIANJI relays for replacement. QIANJI has been specializing in the production of relays for over 20 years, with modern technology and high-quality service guarantees. Click to select relays and get free samples

Summarize

Malfunctioning relays can have a significant impact on equipment operation, but through proper inspection, testing, and maintenance, problems can be detected early and resolved. Whether it is industrial automation or household appliances, choosing reliable high-quality relays can ensure the long-term operation of the equipment.

Visit our industrial relay product page to find the best relay for your application. If you suspect a relay malfunction, please feel free to contact us for professional advice or replacement options.