Omron MY4 6VAC (S) Miniature Power Relay Technical Guide

The Omron MY4 6VAC (S) miniature power relay is a 4PDT plug-in electromechanical relay designed for control panels, automation circuits, machinery interfaces, and general-purpose switching applications where a low-voltage AC control signal is preferred. As part of Omron’s MY series, this relay is known for compact construction, dependable switching behavior, and practical compatibility with socket-based wiring systems.

This model uses a 6 VAC coil and a 4PDT contact arrangement, allowing four separate circuits to be controlled from one coil operation. That makes it especially useful in interlocking circuits, signal multiplication, indication circuits, control logic, and panel retrofit projects where multiple changeover contacts are required in a limited space.

Key Technical Characteristics

The MY4 family is built as a miniature power relay with plug-in terminals. Omron’s MY series documentation identifies MY4 models as four-pole, single-contact plug-in relays, and the MY series supports standard relay formats with and without operation indicators. The 4-pole models are commonly used where several isolated outputs must switch together while maintaining a compact footprint.

For the MY series, Omron specifies high practical durability figures, including fast response behavior, strong insulation performance, and socket mounting options. Typical MY four-pole relay characteristics include a maximum operating time of 20 ms, maximum release time of 20 ms, contact resistance around 50 mΩ maximum, and dielectric strength of 2,000 VAC between coil and contacts for one minute. These values support reliable operation in industrial control environments.

Contact Structure and Switching Capacity

The Omron MY4 6VAC (S) miniature power relay uses a 4PDT contact form, also described as four Form C contacts. This means each pole provides a common, normally open, and normally closed path. In practice, this is valuable when one input signal must simultaneously switch several auxiliary circuits, status lines, safety-related indication loops, or control relays.

For four-pole MY relays, Omron lists contact ratings that include resistive and inductive load categories. The MY4 series is commonly associated with switching up to 250 VAC and 125 VDC maximum contact voltage, with load limits depending on contact type, socket, ambient temperature, and circuit conditions. Inductive loads should always be evaluated carefully because motors, solenoids, contactor coils, and valves create electrical stress during switching.

Where This Relay Is Commonly Used

The Omron MY4 6VAC (S) miniature power relay is often selected for legacy equipment, low-voltage AC control panels, machine rebuilds, burner systems, auxiliary automation circuits, and signal isolation. Its 6 VAC coil makes it suitable for systems where the control transformer or board-level supply already provides a 6 VAC signal.

Because it is socket-mounted, maintenance is easier than with soldered relays. A technician can replace the relay without rewiring the full control circuit, provided the replacement part matches the coil voltage, contact configuration, and socket arrangement.

Installation and Selection Notes

When selecting this relay, confirm the coil voltage first. A 6 VAC coil must not be replaced with a 6 VDC, 12 VAC, or 12 VDC model unless the circuit has been redesigned for that coil type. Also check whether the application requires an operation indicator, latching lever, diode, or CR suppression option.

Socket compatibility is equally important. MY relays are commonly paired with Omron PY and PYF socket families. Socket current ratings may be lower than the relay’s theoretical contact capability, so the socket rating should always be treated as part of the final circuit limit.

For additional Omron relay references, visit Omron components.

FAQ

What type of relay is the Omron MY4 6VAC (S)?

It is a miniature plug-in electromechanical power relay with a 6 VAC coil and 4PDT contact configuration. It is mainly used in control panels and industrial automation circuits.

What does 4PDT mean on this relay?

4PDT means four-pole double-throw. The relay can switch four independent circuits at the same time, with each pole offering normally open and normally closed contact paths.

Can the Omron MY4 6VAC (S) replace a 6 VDC relay?

No. A 6 VAC relay coil and a 6 VDC relay coil are not interchangeable. The coil supply type must match the relay rating to avoid failure or unreliable operation.

Is this relay suitable for inductive loads?

Yes, but inductive loads require careful rating checks. Coils, solenoids, valves, and small motors generate back EMF, so suppression components and proper derating may be required.

Why is socket mounting useful?

Socket mounting allows faster replacement, cleaner wiring, and simpler maintenance. It is especially helpful in control cabinets where downtime must be reduced.

What should be checked before replacement?

Confirm the coil voltage, AC coil type, contact form, contact rating, socket compatibility, terminal layout, and whether the original relay used any indicator or suppression feature.