[System Maintenance Notice]
Due to ongoing system maintenance, the site search and specification search functions are temporarily unavailable. We apologize for any inconvenience this may cause and appreciate your understanding.


Mechanical relay

Basic Structure and Operation Principles

Basic Structure

Sectional drawing

Operation Principle


1.Turn the switch on.

2.Electric current flows to the coil wire wound on the iron core through the coil terminal: The iron core is magnetized.


3.The magnetized iron core draws the armature.

4.The drawn armature, which touches the iron core, pushes the movable contact through the card.


5.When pushed, the movable contact touches the fixed contact, electric current passes through the contact terminal and turns on the bulb.


6.Turning off the switch causes the electric current to stop: The iron core loses the power necessary to draw the armature.

7.The power of the movable spring returns the armature to its original position: The iron core and the armature are separated, turning off the bulb.


1.The coil part and the contact part are completely insulated, forming separate circuits.

  • High insulation, high withstand pressure
  • High resistance against surges and noise
  • No leakage current when opening the circuit
  • Applicable to analog and high frequency signals

2.One input to the coil part simultaneously opens or shuts several independent circuits.

  • Variable contact structures
    HC 4C Type
  • Able to control high capacitive loads

Classification by Protective Structure

Dust Cover Type
To protect from dust, these types are covered, for example, with a plastic case. We recommend hand soldering, because these relays are not constructed to prevent flux and cleaning fluid from entering during automatic soldering.
Flux-Resistant Type
The relay is constructed so that flux will not enter inside the relay during automatic soldering. However, cleaning is not possible.
Sealed Type
Construction is designed to prevent seeping of flux when soldering and cleaning fluid when cleaning. Designed for minimal release of harmful gas at the contacts.
Sealed capsule type
This type is hermetically sealed with ceramic and metal plating. No harmful gas or humidity will ever reach the contacts. This type cannot be washed.

Type Construction Characteristics Automatic Soldering Automatic Cleaning Dust Resistance Harmful Gas Resistance
Dust Cover Type Structure image Most basic construction where the case and base (or body) are fitted together. Caution No Caution No
Flux-Resistant Type Structure image Terminals are sealed or molded simultaneously. The joint between the case and base is higher than the surface of the PC board. Yes No Caution No
Structure image Terminals, case and base are filled with sealing resin.
Construction is not hermetically sealed.
Yes No Caution No
Sealed Type Structure image Sealed construction including terminals and case. The base is sealed with sealing resin. Yes Yes Yes Yes *
Sealed capsule type
(EP and EV relays only)
Structure image Hermetically sealed construction by sealing the metal case and plate, and the terminal and ceramic part, with solder. No No Yes Yes

*Since the plastic material is porous, please avoid atmospheric exposure to silicon.

Classification by Operating Functions

Single Side Stable Type
Relay which turns on when the coil is energized and turns off when de-energized.
Schematic example: DS relay
(Schematic example: DS relay)
1 Coil Latching Type
Relay with latching construction that can maintain the on or off state with a pulse input. With one coil, the relay is set or reset by applying signals of opposite polarities.
Schematic example: DS relay
(Schematic example: DS relay)
2 Coil Latching Type
Relay with latching construction composed of 2 coils: set coil and reset coil. The relay is set or reset by alternately applying pulse signals of the same polarity.
Schematic example: DS relay
(Schematic example: DS relay)
Operation Indication
Indicates the set and reset states (electrically or mechanically) for easy maintenance. Also available are an LED version (HC relay with LED, etc.).
LED type HC relay
LED type HC relay

Terminal Configuration

Mounting Method

Requests to customers (Automation Control Components & Industrial Device) [Excluding specific product]
Requests to customers (Automation Control Components & Industrial Device) [For specific product]
Requests to customers (FA Sensors & Components [Excluding motors])
Requests to customers (Dedicated to industrial motors)