Relay Troubleshooting: Step-by-Step Guide for Electrical Systems > 자유게시판

• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

Testing and diagnosing faulty relays is an essential skill for anyone working with electrical systems, whether in home applications. Relays are simple devices that use a small electrical signal to control a larger electrical load, and when they fail, they can cause everything from an engine that won’t crank.

The good news is that nearly all common relay failures can be identified with common household equipment and a little patience.

Start by understanding the relay’s role in the circuit. Relays typically have five terminals labeled 30, 85, 86, 87, and 87a. Terminal 30 is the main power feed, 85 and 86 are the control windings that receive the trigger voltage, and 87 and 87a are the switched paths. When the coil is energized, the relay switches from the default path to the activated path, switching the load on or off.

The first step in diagnosis is a physical examination. Look for signs of scorching, melting, or corrosion on the relay housing or pins. If you see any damage, the relay is defective and should be swapped out. Also check the connector the relay plugs into. Loose, or corroded pins can create intermittent connections.

Next, use a multimeter to test the relay’s coil. Set your multimeter to measure ohms. Place the probes on terminals 85 and 86. A functioning coil should show a resistance between 50 and 120 ohms, depending on the model. If the reading is OL or less than 10 ohms, the coil is open and the relay must be swapped.

Now check the contacts. With the relay disconnected, place the multimeter probes on terminals 30 and 87a. You should get a reading of no continuity because, in the default position, these contacts are open. Then place the probes on 30 and 87. You should also get an open reading, as 87 is off by default. If you get a closed circuit here, the relay contacts are stuck closed, which is a irreversible damage.

To test the switching function, you need to apply power to the control circuit. You can do this by connecting a 12-volt battery to terminals 85 and 86. You should hear a audible snap as the relay activates. If you hear a silence, the coil is likely dead. If you do hear a click, immediately check continuity again between the switched path. You should now get a closed circuit, indicating the contacts have engaged. If there’s still an open circuit, the switch mechanism are damaged.

Another quick method is the replacement test. If you have a spare relay of the same type, swap it in and see if the system functions. If it does, the original relay was bad. This is especially useful in vehicles where relays are commonly interchangeable.

Always remember to disconnect power before handling or testing a relay. And when in doubt, رله consult the vehicle or equipment manual for the appropriate amperage rating. Some relays are designed for high-cycle applications, and using the unsuitable substitute can cause further damage.

Most relay failures are caused by long-term use, excessive heat, or voltage spikes. Regular cleaning and replacing relays at the earliest symptom of failure can stop cascading failures. Keep a standard automotive relays on hand as backup units, especially if you work with systems that depend on them constantly.

Testing relays isn’t complicated, but it requires precision. By combining visual inspection, multimeter readings, and a practical insight of how relays work, you can accurately identify and replace most relay-related issues.