Finder 77.B3.9.024.8671 – 77 Series Modular solid state relays

Why Choose the Finder 77.B3.9.024.8671 Three-Phase Solid State Relay?

The Finder 77.B3.9.024.8671 is a high-performance 40 A three-phase solid state relay (SSR) designed for reliable, contactless switching of industrial AC loads. Part of the Finder 77 Series, this hockey-puck-style relay combines three-phase semiconductor switching with a low-voltage DC control input, making it suitable for industrial heating, motor control and automated machinery applications.

Featuring a 4–32 V DC control input and a 24–660 V AC output switching range, the Finder 77.B3.9.024.8671 provides an effective interface between electronic control systems and three-phase AC equipment. Its three normally open semiconductor outputs (3PST-NO) are rated at 40 A, subject to appropriate heat-sink selection and operating conditions.

The relay uses random turn-on switching, allowing rapid activation in response to the applied control signal without deliberately waiting for an AC voltage zero crossing. With silent, spark-free and bounce-free operation, screw terminals, a contactor-style terminal arrangement and panel or heat-sink mounting, this model is designed for demanding industrial installations requiring frequent electronic switching.

Key Advantages

• 40 A rated output current for suitably rated three-phase AC loads.
• Three normally open semiconductor outputs for three-phase switching applications.
• 4–32 V DC control input for integration with compatible PLCs and electronic controllers.
• 24–660 V AC switching range for industrial AC equipment.
• 600 V AC rated output voltage for suitable electrical installations.
• Random turn-on operation for rapid response to control signals.
• Silent semiconductor switching without mechanical contact noise.
• Spark-free and bounce-free operation during normal electronic switching.
• High switching endurance without mechanical output contact wear.
• Low control power requirements for electronic automation interfaces.
• Contactor-style terminal arrangement for convenient wiring.
• Panel or heat-sink mounting for flexible installation and thermal management.
• IP20 protection rating for installation within suitable electrical enclosures.

Key Features

• Finder 77 Series industrial solid state relay.
• Model: 77.B3.9.024.8671.
• Three-phase AC switching.
• Output configuration: 3 normally open semiconductor outputs (3PST-NO).
• Rated output current: 40 A.
• Rated output voltage: 600 V AC.
• Load switching voltage range: 24–660 V AC.
• Control input voltage: 4–32 V DC.
• Nominal control voltage: 24 V DC.
• Switching characteristic: Random turn-on.
• Operating frequency range: 47–400 Hz.
• Ambient operating temperature: −30 to +80 °C.
• Off-state leakage current: 10 mA.
• Hockey-puck-style housing.
• Contactor-style terminals: Input and output connections on adjacent sides.
• Screw terminal connections.
• Mounting: Control cabinet panel or suitable heat sink.
• Housing dimensions: 105 × 78 × 36.5 mm.
• Protection classification: IP20.
• Approvals and markings: CE, UKCA, EAC and cURus.

Reliable Three-Phase Random Turn-On Switching for Industrial Automation

The Finder 77.B3.9.024.8671 uses electronic semiconductor switching elements instead of mechanical contacts. When a suitable 4–32 V DC control signal is applied, the relay activates its three semiconductor output paths to control the connected three-phase AC load. Its random turn-on characteristic enables conduction to begin in response to the control signal without intentionally waiting for the next AC voltage zero crossing.

This operating principle makes the relay suitable for applications requiring frequent switching, silent operation and fast electronic control. The 40 A load rating requires appropriate thermal management, including a correctly selected heat sink. Installation must also account for ambient temperature, load characteristics, wiring and protective devices. Because semiconductor outputs can exhibit off-state leakage current, the relay must not be used as a substitute for a mechanical electrical isolator.

Typical Applications

• Three-phase industrial heating equipment.
• Industrial motor control with appropriately rated loads.
• PLC-controlled three-phase AC switching.
• Industrial ovens and drying kilns.
• Heating and cooling process equipment.
• Automated bottling and packaging machinery.
• Labelling and production machinery.
• Industrial lighting control installations.
• Manufacturing and process automation systems.
• Electrical control cabinets and machinery panels.
• OEM equipment requiring frequent, silent semiconductor switching.