Finder 77.B1.9.024.8250 – 77 Series Modular solid state relays

Why Choose the Finder 77.B1.9.024.8250 Solid State Relay?

The Finder 77.B1.9.024.8250 is a 40 A single-phase solid state relay (SSR) designed for contactless switching of AC electrical loads in industrial automation, heating control and machinery applications. Part of the Finder Series 77, this relay features a compact hockey puck-style housing for mounting directly onto a suitable panel surface or heatsink.

Featuring a 3–32 V DC control input and a 24–280 V AC load switching range, the Finder 77.B1.9.024.8250 provides an effective interface between low-voltage DC control systems and higher-voltage AC loads. Its single normally open (1 NO / SPST-NO) semiconductor output supports a maximum load current of 40 A, subject to appropriate thermal management and manufacturer-specified operating limits.

The relay incorporates zero-cross switching, which initiates conduction close to the AC voltage zero crossing to help reduce switching disturbances with suitable loads. Its contactless operation provides silent, bounce-free switching, while the protective terminal cover and IP20 construction support integration into professionally designed electrical control assemblies.

Key Advantages

• 40 A maximum load current for appropriately rated single-phase AC loads.
• 3–32 V DC control input for compatible PLC outputs, electronic controllers and DC control circuits.
• 24–280 V AC load switching range for industrial electrical applications.
• Zero-cross switching helps minimise switching disturbances when controlling suitable loads.
• Contactless semiconductor operation eliminates mechanical contact bounce.
• Silent switching without mechanical relay contact noise.
• High switching endurance without mechanical contact wear.
• Hockey puck-style housing for direct mounting onto suitable panels or heatsinks.
• Fold-out terminal cover provides additional protection around electrical connections.
• Input and output terminals on opposite sides for organised wiring.
• LED indication for convenient local monitoring.
• IP20 degree of protection for installation within suitable electrical enclosures.
• Compact 45 mm × 59 mm × 29.4 mm construction for industrial panel integration.

Key Features

• Finder Series 77 solid state relay.
• Type 77.B1 hockey puck-style construction.
• Maximum load current: 40 A.
• Nominal control voltage: 24 V DC.
• Control input voltage range: 3–32 V DC.
• Switched load voltage range: 24–280 V AC.
• Output configuration: 1 NO (SPST-NO).
• Number of switched phases: 1.
• Switching method: Zero-cross switching.
• Semiconductor switching technology for contactless operation.
• Panel or heatsink mounting using the hockey puck-style housing.
• Fold-out screw terminal cover.
• Screw terminal electrical connections.
• LED status indication.
• 4,000 V AC input-to-output dielectric strength.
• IP20 degree of protection.
• Operating ambient temperature: −30 °C to +80 °C.

Reliable 24 V DC-Controlled Switching for Industrial Heating and Automation

The Finder 77.B1.9.024.8250 provides electronic switching of AC electrical loads using semiconductor technology rather than mechanically operated contacts. Applying a suitable signal within its 3–32 V DC control range activates the switching circuit, allowing compatible industrial controllers and PLC outputs to control AC loads without requiring a conventional electromechanical relay.

Its zero-cross switching characteristic initiates conduction near the AC voltage zero crossing, making the device particularly suitable for compatible resistive heating applications. The absence of mechanical contacts also eliminates contact bounce and mechanical switching noise, supporting repeated switching operations in industrial process control systems.

As a 40 A solid state relay, the device requires careful consideration of heat dissipation. Its maximum load rating depends on suitable thermal management, including the use of an appropriately sized heatsink where required. Installation must account for ambient temperature, load characteristics, upstream protection and manufacturer-specified derating. The relay also does not provide galvanic load isolation when switched off, so a separate suitable isolating device is required wherever safe electrical isolation is necessary.

Typical Applications

• Industrial resistance heating systems.
• Electric heater and heating element control.
• Industrial ovens and process heating equipment.
• Temperature-controlled machinery.
• PLC-controlled AC load switching.
• Industrial automation control panels.
• Compatible lighting and lamp switching applications.
• Solenoid and contactor driving circuits.
• Packaging and manufacturing machinery.
• Production line electrical switching equipment.
• OEM machinery and electrical panel manufacturing.
• Applications requiring silent, contactless AC switching from a DC control signal.