how to test communication relay with multimeter： a step-by-step guide
Release time:2025-09-13 15:26:32
Testing a communication relay with a multimeter is an essential procedure for ensuring that the relay is functioning correctly and the communication circuits are operational. Relays are commonly used in communication systems to switch signals, protect circuits, and control different parts of an electrical system. When a relay fails, it can cause disruptions in the entire communication network. A multimeter, which is an indispensable tool for electrical testing, can help diagnose relay problems by measuring resistance and continuity. This article provides a step-by-step guide on how to test a communication relay using a multimeter.
1. Understand the Relay's Components
Before starting the test, it's essential to understand the basic components of the relay. A communication relay typically consists of the following：
Coil： This is the electromagnetic part of the relay that gets energized to activate the switching mechanism.
Common (COM)： This is the central contact point that connects to the circuit.
Normally Open (NO)： This contact remains open when the relay is de-energized but closes when the relay is activated.
Normally Closed (NC)： This contact remains closed when the relay is de-energized but opens when the relay is activated.
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