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How to distinguish electromagnetic relays from solid state relays

  • Author:o-leading.
  • Source:o-leading.com
  • Release on :2019-02-15


Do you know how to judge the quality of electromagnetic relays and solid state relays? The corresponding methods for detecting relay coils, relay nodes, and detecting solid state relays are described below.
A relay is a commonly used control device that can control a large current with a small current, a high voltage with a low voltage, an alternating current with a direct current, and the like, and can realize a control circuit and a controlled circuit. Complete isolation, widely used in circuit control, protection circuits, automatic control and remote control.


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There are many types of relays, including electromagnetic relays, reed relays, piezoelectric relays, and solid state relays.

The node form of the relay is divided into three types: the moving node, the breaking node, and the switching node.
A relay can have a set of nodes or several sets of nodes. These nodes can be
The moving node can also be a breaking node or a conversion node.


When the relay is activated, all nodes operate at the same time.
The relay can be detected with a multimeter resistance file, including the coil junction of the detection relay.
First, the detection of electromagnetic relay

1, detecting relay coil
Place the multimeter in the "Rx100" or "Rx1k" file. The two test leads (not positive or negative) are connected to the two pins of the relay coil. The DC resistance of the relay coil is measured. The multimeter pointer indicates that it should basically match the coil resistance of the relay. .
If the gauge indicates that the resistance is significantly smaller, the relay coil is partially short-circuited. If the gauge indicates that the resistance is zero, it indicates a short circuit between the two pins of the relay coil. If the gauge indicates that the resistance is infinite, the relay coil is open. All three cases indicate that the relay is damaged.


2, detection relay node
Connect the relay coil to the specified working voltage, and use the multimeter "Rx1K" file to detect the continuity of the node.
When the operating voltage is not applied to the relay coil, the normally open node should not be connected, and the normally closed node should be turned on. When the working voltage is added, the relay should be able to hear the sound of the connection. At this time, the normally open contact should be turned on, the normally closed node should be unreachable, and the replacement node should be switched accordingly. Otherwise, the relay is damaged. For multiple sets of node relays, if some of the nodes are damaged and the remaining nodes are functioning normally, they can still be used.




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Second, the detection of solid state relays
Solid state relay (SSR) is a new type of electronic relay. It uses electronic circuits to realize the function of relays. It relies on optocouplers to achieve isolation between control circuits and controlled circuits. Solid state relays are divided into two major categories: DC and AC.
When detecting a solid state relay, place the multimeter in the "Rx1K" position and detect its input and output sections, respectively.

1, detection input part
Check the input part of the solid state relay as shown in the figure below. Use a multimeter to measure the forward and reverse resistance between the two pins of the solid state relay input terminal. The forward resistance is small and the reverse resistance is large.

2, detection output part
Check the output of the solid state relay as shown in the figure below. Use a multimeter to measure the positive and negative resistance between the two pins of the solid state relay output, which should be infinite.


3. Dynamic detection of solid state relays (Single PCB   manufacturer china)
On the basis of the previous step detection, the input voltage of the solid state relay is connected to the specified working voltage. At this time, the two pins of the output of the solid state relay should be turned on, and the multimeter pointer indicates that the resistance is small.
After disconnecting the working voltage of the input terminal of the solid state relay, the output pin should be cut off between the two pins, and the multimeter pointer is infinite.