Omron MY4 24VAC (S) General Purpose Relay for Industrial Control Circuits
The Omron MY4 24VAC (S) general purpose relay is a plug-in electromechanical relay designed for control panels, machine automation, HVAC equipment, signal switching, and auxiliary circuit logic. It is part of Omron’s MY relay series, a widely used family of miniature power relays built for reliable switching in industrial environments. With a 24 VAC coil and 4PDT contact configuration, this relay is useful when one control signal must operate several independent circuits at the same time.
This model is often selected for low-voltage AC control systems where safer panel-level control voltage is preferred instead of mains-level coil operation. The 4PDT contact layout provides four changeover contacts, which gives engineers flexibility in panel design. A single relay can switch indicator lamps, interlocks, alarms, control signals, or auxiliary loads while keeping circuits electrically separated.
Technical Overview
The Omron MY4 24VAC (S) relay uses a 24 VAC coil and a plug-in terminal structure. It is commonly described as a miniature power relay for sequence control and power switching applications. The contact form is 4PDT, also known as four-pole double-throw. This means each pole can switch between normally closed and normally open paths when the coil is energized.
The relay is designed for socket-based installation, which helps reduce wiring time and simplifies maintenance. If a relay fails or reaches the end of its service life, the unit can usually be replaced without rewiring the entire circuit, provided the correct socket and wiring arrangement are already in place.
Main Application Areas
The Omron MY4 24VAC (S) general purpose relay is suitable for control cabinets, industrial machines, HVAC panels, water treatment systems, conveyor controls, alarm panels, lighting automation, and signal conversion circuits. It can also be used in applications where a control transformer provides 24 VAC power for relay coils.
Because of its four-pole structure, this relay is valuable when several control actions must happen together. For example, energizing the relay may activate a pilot lamp, send a status signal, interrupt a safety-related auxiliary path, and switch a secondary control circuit. This makes the relay practical for compact panel designs where space, serviceability, and circuit organization matter.
Key Features
- Brand and model: Omron MY4 24VAC (S)
- Product type: General purpose electromechanical relay
- Coil voltage: 24 VAC
- Contact form: 4PDT
- Installation style: Plug-in relay for socket mounting
- Typical use: Industrial control and auxiliary switching
- Relay family: Omron MY miniature power relay series
Engineering Considerations
Before using the Omron MY4 24VAC (S), the control voltage must be confirmed. A 24 VAC coil should only be used in circuits designed to energize a 24 VAC relay. It should not be interchanged with a 24 VDC relay unless the coil supply and wiring are correctly changed. Although AC and DC coil ratings may look similar at first glance, they are electrically different and must not be treated as direct substitutes.
Load type is also important. Resistive loads are generally easier for relay contacts to switch, while inductive loads such as contactor coils, solenoids, and electromagnetic valves can create electrical stress during turn-off. In those cases, suitable suppression components and correct derating practices help improve contact life and switching reliability.
For related Omron components, sockets, and industrial relay options, see Omron automation products.
FAQ
What is the Omron MY4 24VAC (S) used for?
It is used to switch several control circuits from one 24 VAC coil signal. Typical applications include automation panels, HVAC controls, auxiliary relay logic, alarm circuits, interlocking systems, and machine control panels.
Is the Omron MY4 24VAC (S) a 4PDT relay?
Yes. It has a 4PDT contact configuration, giving four changeover contacts in one relay body. This allows one coil signal to control four separate switching paths.
Can Omron MY4 24VAC (S) replace a 24VDC relay?
No. A 24 VAC relay and a 24 VDC relay are not direct replacements. The coil supply must match the relay coil rating. Using the wrong coil voltage can cause malfunction, overheating, or failure.
Why is socket mounting useful?
Socket mounting makes installation and maintenance easier. The relay can be removed from its socket without disconnecting each wire, which helps reduce downtime in industrial panels.
Is this relay suitable for HVAC control panels?
Yes, it can be suitable when the HVAC system uses 24 VAC control voltage and the relay contact ratings match the connected loads. Designers should always verify the circuit requirements before installation.
What should be checked before installation?
The coil voltage, contact rating, socket compatibility, load type, current demand, operating temperature, vibration conditions, and wiring diagram should all be checked before installation.
Does the Omron MY4 24VAC (S) work with control transformers?
Yes, it is commonly used in circuits where a control transformer provides 24 VAC power. The transformer capacity and control circuit design must be suitable for the relay coil and other connected devices.