Electromagnetic Relay

Electromagnetic relay, EMR for short, controls the current through a coil to produce electromagnetic attractive force that drives the moveable part of the magnetic circuit. Then it achieves the opening, closing or switching of the contact.


Refer to diagram 1 of its working characteristic.

Diagram 1-Working Characteristic


No matter what the structures of electromagnetic relays are, they are composed of inductive part(to receive input signal), comparative part(to provide comparison) and executive part(to output circuit).


Refer to diagram 2 of its working theory.

Diagram 2-Working Theory


Notice for Purchasing

1. Model Number Structure

Model Number Legend-Electromagnetic Relay

2. Combination Forms of Common Contact

Name Definition Structure Form Symbol Code
Normally Open Contact Contact group that makes controlled circuit open after relay operates  Normally Open Contact Symbol-Normally Open Contact H A
Normally Closed Contact Contact group that makes controlled circuit closed after relay operates  Normally Closed Contact Form Symbol-Normally Closed Contact D B
Transferable Contact Contact group that makes one controlled circuit break at first, then makes another controlled circuit closed Transferable Contact Form Symbol-Transferable Contact Z C


3. Load Property and Surge Current

Characteristics Surge Current Surge Time(s) Remark
Resistance Steady State Current / L ≤ 10-4H or COSF = 1
Inductivity 3~5 Times of Steady State Current 1~50 /
Electric Motor 5~10 Times of Steady State Current 0.2~0.5 Can use 5~6 times resistant load instead for testing
Lamp Property 10~15 Times of Steady State Current 1 /
Capacity 20~40 Times of Steady State Current 1~50 Long transmission line, filter and power supply should be considered as capacitive load
Wave Surging Current Wave


4. Installation Mode

Installation Mode Structure Form Product Model Remark
Welding Type Welding Form Tip leading out terminal type of relay Including PCB type
Socket Type Socket Form HH Series, 13F Series, LR Series, MK, JTX-10F, JQX-38F, JQX40-2Z Including socket type
Screw Type Screw Form JQX-40/1Z, JQX-59F, JQX-60F, JQX-62F, JQX-63F, JQX-80F /