Finder 22.21.9.012.4000 – 22 Series Modular monostable relays

Finder 22.21.9.012.4000 – 20 A Modular Contactor with 12 V DC Coil

The Finder 22.21.9.012.4000 is a compact 20 A modular contactor with a 12 V DC operating coil, designed for switching suitable electrical loads in distribution boards, control panels and automated installations. Part of the Finder 22 Series, this electromagnetic contactor provides a practical interface between a low-voltage DC control circuit and a separately supplied electrical load.

Featuring one normally open contact (1 NO), the contactor closes its switching contact when the correct coil voltage is applied and returns to its normally open position when the coil is de-energised. Its compact, single-module format makes it especially useful where DIN rail space is limited.

The 12 V DC coil distinguishes this version from AC-coil variants in the same product family. It is suitable for appropriately designed control systems that provide a regulated 12 V DC operating signal, including relay interfaces, automation controllers and compatible power-supply arrangements.

With silver tin oxide (AgSnO₂) contacts, a 35 mm DIN rail mounting arrangement and conventional screw terminal connections, the Finder 22.21.9.012.4000 is designed for dependable electrical switching in residential, commercial and light industrial environments.

Key Advantages

• 20 A modular contactor for suitable electrical switching applications.
• 12 V DC operating coil for compatible low-voltage control circuits.
• One normally open contact for straightforward single-pole switching.
• AgSnO₂ contact material for robust electrical switching characteristics.
• Compact DIN rail design helps conserve space in electrical enclosures.
• Monostable operation automatically returns the contact to its normal state when coil power is removed.
• Allows a low-voltage controller to operate a separate, appropriately rated load circuit.
• Suitable for integration with compatible timers, relays and building automation equipment.
• Conventional screw terminals simplify installation and maintenance.
• No integrated programming or network configuration required.
• Useful for panel building, equipment replacement and electrical system upgrades.

Key Features

• Manufacturer: Finder.
• Series: 22 Series modular contactors.
• Model: 22.21.9.012.4000.
• Contact arrangement: 1 normally open (1 NO / SPST-NO).
• Rated contact current: 20 A.
• Nominal operating coil voltage: 12 V DC.
• Contact material: Silver tin oxide (AgSnO₂).
• Operating principle: Electromagnetic, monostable.
• Mounting: 35 mm DIN rail.
• Housing format: Compact, approximately one modular width.
• Electrical connections: Screw terminals.
• Switching behaviour: Contact closes while the coil is energised.

How the 12 V DC Modular Contactor Works

The Finder 22.21.9.012.4000 operates using an electromagnetic coil and a mechanically linked switching contact.

When a suitable 12 V DC control supply is applied to the coil, the electromagnetic mechanism moves the contact into its operated position. Because the contact arrangement is normally open, energising the coil closes the contact and completes the connected load circuit.

When the control supply is removed, the mechanism releases and the contact opens again.

This makes the contactor suitable for applications where a load should remain energised only while the control signal is present.

For example, a compatible low-voltage automation controller could energise the coil in response to a programmed condition. The contactor would then close its separate switching contact to operate an appropriately rated electrical circuit.

The contactor does not contain a latching mechanism, built-in timer or programmable controller. Its switching state follows the presence or absence of the coil supply.

12 V DC Coil for Low-Voltage Control Systems

The defining feature of the 22.21.9.012.4000 is its 12 V DC operating coil.

This is particularly useful where the control system operates at a low DC voltage rather than directly from a mains AC supply.

Potential control sources include appropriately rated DC power supplies, relay interfaces, automation outputs and other switching devices capable of supplying the contactor's required coil current.

The coil voltage must not be confused with the voltage of the load circuit. The coil determines how the contactor is operated; the main contact determines which electrical load can be switched.

A 12 V DC coil must not be connected directly to a 230 V AC supply. Likewise, a controller designed for a different coil voltage should not be assumed suitable.

Before installation, verify the control supply voltage, available current, polarity requirements where applicable, and any recommended coil suppression arrangements against the current Finder datasheet.

20 A Normally Open Switching Contact

The Finder 22.21.9.012.4000 provides one normally open switching contact rated at 20 A.

A normally open contact remains open when the coil is not energised. When the correct operating voltage is applied, the contact closes and permits current to flow through the controlled circuit.

This configuration is useful for straightforward switching applications where only one electrical conductor or one load circuit needs to be controlled.

The 20 A rating must be interpreted alongside the relevant utilisation category, load voltage and electrical characteristics of the connected equipment.

Resistive loads, motors, transformers and electronic lighting drivers can place substantially different demands on a switching contact. A circuit drawing less than 20 A during normal operation may still generate a much higher starting or inrush current.

For this reason, the connected equipment must be checked against Finder's application-specific switching ratings. The contactor should not be selected solely by comparing its nominal current rating with the running current of the load.

Silver Tin Oxide Contact Material

The .4000 variant uses AgSnO₂ silver tin oxide contact material.

Silver tin oxide is commonly used in electrical switching devices because of its performance under suitable switching conditions, including applications involving elevated current transients.

In a modular contactor, contact material is an important consideration because the switching surfaces must repeatedly make and break the electrical circuit.

AgSnO₂ contacts can offer useful resistance to contact welding compared with certain other contact compositions, although the actual performance depends on the complete contact design and the electrical load.

Contact material does not eliminate the need to check switching capacity, inrush current and operating frequency. Where particularly demanding loads are involved, additional switching protection or a different contactor rating may be necessary.

Compact DIN Rail Installation

The Finder 22.21.9.012.4000 is intended for mounting on a standard 35 mm DIN rail inside a suitable electrical enclosure.

Its compact modular housing makes it practical for distribution boards and control panels where available rail space is limited.

Because the contactor provides only one normally open contact, it is particularly appropriate where a single switching circuit is required and a larger multi-pole device would be unnecessary.

The screw terminals provide conventional electrical connections for the coil and load circuit.

During installation, the electrician should ensure that the conductors are correctly sized, the terminals are tightened according to Finder's instructions and the electrical enclosure provides suitable protection against accidental contact.

Consideration should also be given to heat generated by adjacent equipment, enclosure ventilation and any applicable derating requirements.

Integration with Electrical Automation Systems

The Finder 22.21.9.012.4000 can act as an interface between a low-voltage control device and a separate electrical load.

For example, an automation controller operating at 12 V DC may use a suitable output stage to energise the contactor coil. The contactor then performs the required switching through its main contact.

This arrangement can be useful when the control device's output is not intended to switch the load directly.

Applications may include timed equipment operation, lighting control, auxiliary electrical switching and selected building management functions.

However, the contactor itself does not provide any communication protocol, remote access facility or programmable logic.

Those capabilities must be supplied by compatible external control equipment.

Where a controller uses a semiconductor output rather than a mechanical relay output, the installer must confirm that the output can drive the coil correctly and tolerate any switching transients.

Installation and Compatibility Considerations

Before installing the Finder 22.21.9.012.4000, verify that the intended control circuit supplies the correct 12 V DC coil voltage and that the connected load is compatible with the contact ratings.

The electrical load circuit and control circuit must be wired according to the manufacturer's terminal diagram.

Because this is a single-pole, normally open contactor, it does not provide two-pole isolation or simultaneous switching of multiple circuits.

It is not an overload relay, circuit breaker, residual current device or protective isolator. Appropriate electrical protection must be provided separately.

Where the controlled equipment requires safety-rated disconnection, emergency stopping or another specialised protective function, a device approved for that purpose must be used.

Installation and maintenance should be carried out by a competent electrician with all relevant supplies isolated and verified safe.

Choosing the Correct Finder 22.21 Variant

The Finder 22 Series includes contactors with different operating coil voltages and contact configurations.

The Finder 22.21.9.012.4000 is specifically intended for systems requiring a 12 V DC coil and one normally open contact.

It should not be confused with the Finder 22.21.8.240.4000, which belongs to the same general modular contactor family but uses a 240 V AC coil.

Although two devices may share a similar contact arrangement and housing, their coil supplies are not interchangeable.

When replacing an existing contactor, always compare the complete manufacturer part number, coil voltage, contact configuration, contact material and load ratings.

For installations requiring a normally closed contact or multiple switched poles, select a suitable alternative configuration rather than adapting the wiring to an incompatible contactor.

Typical Applications

• Low-voltage DC controlled switching systems.
• Electrical distribution boards.
• Control panel construction.
• Building automation interfaces.
• Compatible lighting control circuits.
• Timed electrical load switching.
• Auxiliary equipment control.
• Residential and commercial electrical installations.
• Suitable heating control circuits.
• Relay-based automation systems.
• Maintenance and replacement of compatible 12 V DC contactors.
• Compact DIN rail control assemblies.