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Lead Contents

General-purpose Relay: MY4H and MY4

FAQ No. FAQ02758

Primary Contents

Question

What is the difference between MY4H and MY4 General-purpose Relays?

Answer

MYH-series General-purpose Relays are encased in a sealed metal structure containing nitrogen gas. A metal case is used to provide resistance against harmful corrosion to prevent corrosive gases from penetrating the Relays.

Classification by Type of Protection

ItemFeaturesRepresentative
model
Atmosphere conditions
Mounting
structure
Type of
protection
Dust and dirtCorrosive
gases
Plug-in
Relays
Unsealed
(cased)
Structure that protects against
contact with foreign material by
means of enclosure in a case
(designed for manual soldering)
MY
Some protection
(No large dust or
dirt particles
inside Relay.)
No protection
Plastic
sealed
Structure sealed with resin case
or cover that provides resistance
against atmospheres containing
corrosive gases affecting the Relay
G2A-434
OKOK
See note.
Hermetically
sealed
Structure with metal or glass
enclosure and base hermetically
sealed with inert gas (N2) that
provides resistance against
harmful corrosion to prevent
corrosive gases from penetrating
the Relay
MYH
OKOK
Screw
(metal)-
mounting
Relays
OpenStructure that provides protection
against contact and penetration of
foreign matter
MM2
No protectionNo protection
Enclosed
(cased)
Structure that protects against
contact with foreign material by
means of enclosure in a case
(designed for manual soldering)
G7J
Some protection
(No large dust or
dirt particles
inside Relay.)
No protection

Note:

Using Relays in an Atmosphere Containing Corrosive Gas
(Silicon, Sulfuric, or Organic Gas)

Do not use Relays in a location where silicon gas, sulfuric gas (SO2 or H2S), or organic gas is present.

If Relays are stored or used for an extended period of time in an atmosphere of sulfuric gas or organic gas, contact surfaces may become corroded and cause contact instability and obstruction, and terminal soldering characteristics may be degraded.

Also, if Relays are stored or used for an extended period of time in an atmosphere of silicon gas, a silicon film will form on contact surfaces, causing contact failure.

The effects of corrosive gas can be reduced by the processing shown in the following table.

ItemProcessing
Outer case, housingSeal structure using packing.
RelayUse a Plastic Sealed Relay (except in silicon atmospheres) or a Hermetically Sealed Relay.
PCB, copper platingApply coating.
ConnectorsApply gold plating or rhodium plating.