40.61.7.110.4021 Finder Miniature PCB relay 1pole 16A DC 110V

Finder 40.61.7.110.4021 – 110 V DC 16 A Miniature PCB Relay, 1CO, AgSnO₂, Wash-Tight

The Finder 40.61.7.110.4021 is a professional 110 V DC miniature electromagnetic power relay designed for dependable electrical switching in industrial automation, electronic control equipment and printed circuit board assemblies. Part of the Finder 40 Series, this relay combines a 16 A rated contact current, one changeover contact (1CO / SPDT) and a sensitive DC coil in a compact, PCB-compatible housing.

This specific version features silver-tin oxide (AgSnO₂) contact material, providing robust switching performance in applications involving demanding electrical loads. Its 110 V DC control coil makes it suitable for compatible industrial DC control systems, while the changeover contact allows a separate load circuit to be switched without carrying load current through the control electronics.

The 40.61.7.110.4021 also incorporates RT III wash-tight construction and 3.5 mm PCB terminal pins. These characteristics make it particularly suitable for electronic equipment manufacturing, including through-hole soldering and compatible PCB cleaning processes.

With its 500 mW sensitive DC coil, reinforced coil-to-contact insulation and compact miniature housing, the Finder 40.61.7.110.4021 provides an effective switching solution for engineers requiring reliable control of compatible electrical loads.

Key Advantages

• 16 A rated contact current for compatible electrical loads.
• 110 V DC sensitive coil for industrial DC control systems.
• One changeover contact (1CO / SPDT) for flexible switching.
• Silver-tin oxide (AgSnO₂) contacts for demanding switching applications.
• High short-duration inrush-current capability on the normally open contact.
• 500 mW nominal coil consumption for efficient control operation.
• RT III wash-tight construction for compatible PCB cleaning processes.
• 3.5 mm terminal pins designed for direct PCB soldering.
• Monostable operation provides a defined de-energised contact position.
• Reinforced coil-to-contact insulation for electrical separation.
• 6 kV impulse withstand capability between coil and contacts.
• 8 mm creepage and clearance design between control and load circuits.
• Compact miniature housing reduces PCB space requirements.
• 5 mm contact terminal pitch supports PCB integration.
• Suitable for industrial electronics and automation equipment.

Key Features

• Finder 40 Series miniature power relay.
• Type 40.61 single-pole relay construction.
• 110 V DC nominal coil voltage.
• Sensitive DC coil configuration.
• 500 mW nominal coil power.
• Approximately 23.5 kΩ nominal coil resistance.
• Approximately 4.7 mA nominal coil current.
• One changeover contact.
• SPDT / Form C contact arrangement.
• 16 A rated contact current.
• 250 V AC rated contact voltage.
• 400 V AC maximum switching voltage.
• 4,000 VA rated AC-1 switching capacity.
• Silver-tin oxide (AgSnO₂) contact material.
• Up to 120 A for 5 ms peak-current capability on the normally open contact, under specified conditions.
• Monostable, non-latching operation.
• RT III wash-tight environmental protection.
• 3.5 mm PCB terminal pin length.
• 5 mm contact pin pitch.
• Reinforced coil-to-contact insulation.
• 6 kV coil-to-contact impulse withstand.
• Direct through-hole PCB mounting.

How the Finder 40.61.7.110.4021 Relay Works

The Finder 40.61.7.110.4021 uses an electromagnetic coil to operate a mechanical changeover contact. The 110 V DC coil acts as the control input, while the relay contacts provide a separate switching circuit for a compatible electrical load.

When the coil is de-energised, the common contact is connected to the normally closed (NC) terminal. Applying the correct DC control voltage energises the coil, creating a magnetic field that moves the relay armature and transfers the common contact to the normally open (NO) terminal.

When the coil voltage is removed, the spring mechanism returns the contact to its original position. This monostable operating principle means that the relay does not retain its energised contact state after the control supply is disconnected.

The relay's sensitive DC coil consumes approximately 500 mW at its nominal operating voltage. With a nominal coil resistance of approximately 23.5 kΩ, the coil draws around 4.7 mA at 110 V DC.

Although the coil current is relatively low, its 110 V DC operating voltage requires a suitably rated control circuit. The coil must not be connected directly to low-voltage microcontroller outputs or an AC supply.

Where semiconductor electronics control the relay, an appropriately rated flyback diode or alternative transient suppression arrangement should be considered. The suppression method must be suitable for the coil voltage and the required relay release characteristics.

16 A Switching Performance and AgSnO₂ Contacts

The Finder 40.61.7.110.4021 features a 16 A changeover contact manufactured using silver-tin oxide (AgSnO₂). This contact material is valued for its resistance to contact welding and its suitability for certain loads that produce substantial switching inrush currents.

The Finder 40.61 family provides a rated 4,000 VA AC-1 switching capacity, corresponding to its general resistive-load capability at the rated AC contact voltage.

For the AgSnO₂ contact version, Finder specifies a maximum short-duration peak current of 120 A for 5 ms on the normally open contact. This rating is intended for specific switching conditions and must not be interpreted as a continuous 120 A rating.

Electrical loads such as LED drivers, switch-mode power supplies, transformers and capacitive input circuits can draw significantly more current at switch-on than during normal operation. The AgSnO₂ contact material can be beneficial in suitable applications, but the connected equipment's inrush current must still be checked against Finder's applicable switching limits.

The relay's 16 A rated current is also not a universal rating for every load type. Inductive loads, motor loads and DC circuits may have substantially different permitted switching currents.

For DC load switching, particular care is required because electrical arcs can be more difficult to interrupt. The 110 V DC coil rating refers to the control circuit and does not establish the allowable DC voltage or current at the contacts.

RT III Wash-Tight PCB Construction

The Finder 40.61.7.110.4021 incorporates RT III wash-tight construction, making it suitable for compatible electronic manufacturing processes where printed circuit boards are cleaned after soldering.

The relay features 3.5 mm terminal pins intended for direct through-hole PCB soldering. These shorter pins distinguish it from the longer-pin plug-in versions of the Finder 40.61 family.

As a result, the 40.61.7.110.4021 should be treated as a direct PCB mounting relay, rather than assumed to fit a standard Finder 95 Series plug-in socket.

The compact relay body measures approximately 29 × 12.4 × 25 mm, making it suitable for equipment where high-current switching must be accommodated within limited PCB space.

PCB designers should follow Finder's recommended terminal layout and provide suitable conductor track widths, copper thickness, insulation distances and thermal management for the intended electrical load.

The RT III wash-tight designation relates to the relay's construction for compatible manufacturing and cleaning processes. It is not an IP rating for an installed electrical enclosure and does not mean that the relay can be exposed directly to outdoor weather or unrestricted moisture.

Reinforced Insulation and Electrical Safety

The Finder 40.61 relay family incorporates reinforced insulation between the coil and contact circuits, with an 8 mm creepage and clearance design and a 6 kV impulse withstand capability.

These characteristics support electrical separation between the control and load circuits when the relay is incorporated into a correctly designed electrical assembly.

The relay also provides a published 1,000 V AC dielectric strength between open contacts. The finished product must nevertheless meet the applicable electrical safety standards and include suitable overcurrent protection, conductor spacing and enclosure arrangements.

When replacing an existing relay, engineers should verify the coil voltage, contact material, contact arrangement, PCB terminal length and environmental protection version. Relays from the same Finder 40.61 family are not necessarily interchangeable simply because they have the same rated contact current.

Typical Applications

• Industrial automation control boards.
• 110 V DC industrial control circuits.
• PCB-mounted electrical load switching.
• Electronic equipment manufacturing.
• Industrial machine control electronics.
• Building automation equipment.
• Electrical signal changeover circuits.
• Control of appropriately rated lighting equipment.
• Switching compatible LED drivers and electronic power supplies.
• Power management and control assemblies.
• Industrial monitoring and alarm equipment.
• Remote electrical switching systems.
• Electronic instrumentation and control equipment.
• Professional PCB manufacturing and cleaning processes.
• Maintenance of compatible industrial electronic assemblies.