Omron MY3 12VAC General Purpose Relay
The Omron MY3 12VAC general purpose relay is a compact electromechanical relay built for low-voltage AC control circuits. It is part of the Omron MY miniature relay series and is commonly used in control panels, signal switching systems, machine interfaces, and auxiliary automation circuits that operate with a 12 VAC control supply.
This relay uses a 3PDT contact form, allowing three independent changeover circuits to be controlled by a single 12 VAC coil. For panel builders and maintenance engineers, this makes the relay useful in applications where several related control signals must change state together.
Technical Overview
Omron identifies the MY3 AC12 as a miniature power relay with plug-in terminals, a 3-pole structure, single contact method, silver contact material, and 3PDT contact form. The relay is rated for 220 VAC 5 A on resistive AC loads and 24 VDC 5 A on resistive DC loads. For inductive loads, the rating is lower, so the load type must always be reviewed before final circuit approval.
The 12 VAC coil draws different current depending on line frequency. Omron lists 106.5 mA at 50 Hz and 91 mA at 60 Hz. This detail matters when choosing transformers, control power supplies, and protective components in low-voltage AC panels.
Why 12 VAC Matters
A 12 VAC relay is often used where low-voltage control is preferred for safety, isolation, or compatibility with existing equipment. It may appear in small machine controls, interface panels, HVAC-related circuits, alarm signaling, and transformer-fed auxiliary systems. The low coil voltage does not change the need for correct contact load evaluation; the contacts must still be matched to the load being switched.
Practical Use in Control Panels
The plug-in terminal design makes the Omron MY3 12VAC general purpose relay easier to maintain than hardwired relay formats. When used with a compatible socket, the relay can be removed and replaced without rewiring the entire circuit. This is valuable in panels where uptime, clean wiring, and fast troubleshooting are priorities.
The 3PDT arrangement is useful when one control event must trigger several circuit changes. For example, one coil signal may activate an alarm path, change an interlock state, and send a feedback signal at the same time. This helps reduce component count and keeps the control logic organized.
Omron MY3 12VAC For more background on compatible Omron relay products, see Omron component information.
Omron MY3 12VAC FAQ
What is the Omron MY3 12VAC relay used for?
It is used for low-voltage AC control switching in automation panels, machine circuits, signal routing, HVAC controls, and auxiliary electrical systems.
Is this relay designed for 12 VDC?
No. This specific version is for 12 VAC coil operation. A 12 VDC control circuit requires the DC coil version, not the AC coil version.
What is the contact form of the MY3 12VAC?
The contact form is 3PDT, meaning three separate changeover contacts operate together when the coil is energized.
Can it switch 220 VAC loads?
Yes, within the specified rating. Omron lists 220 VAC 5 A for resistive loads. Inductive loads require lower current ratings and suitable circuit protection.
Why does coil current change between 50 Hz and 60 Hz?
AC relay coils respond differently depending on frequency. Omron therefore provides separate current values for 50 Hz and 60 Hz operation.
Is socket mounting recommended?
Yes. Plug-in socket mounting improves serviceability, supports cleaner wiring, and allows faster relay replacement during maintenance.