Finder 77.D1.8.230.8250 – 77 Series Modular solid state relays

Why Choose the Finder 77.D1.8.230.8250 Solid State Relay?

The Finder 77.D1.8.230.8250 is a high-current 60 A single-phase solid state relay (SSR) designed for reliable, silent switching of AC electrical loads in industrial automation, process heating and machinery control applications. Part of the Finder 77 Series, this semiconductor switching device offers a durable alternative to conventional electromagnetic relays where frequent switching, reduced mechanical wear and quiet operation are important.

Featuring a 90–280 V AC control input and a 24–280 V AC load switching range, the Finder 77.D1.8.230.8250 is particularly suitable for systems using a mains-voltage control signal. Its zero-cross switching technology activates the output near the AC waveform's zero-voltage point, helping to reduce switching-related electrical disturbances in suitable resistive load applications.

With a 60 A rated output current, a single normally open equivalent output and a compact hockey puck-style housing, this Finder solid state relay is designed for panel or heatsink mounting. Its screw terminals, protective folding covers and robust industrial construction make it a practical solution for electric heater control, industrial ovens, lighting circuits and automated production equipment. Appropriate heatsinking is essential when operating at elevated load currents.

Key Advantages

• 60 A rated output current for high-current AC switching applications, subject to thermal derating.
• 90–280 V AC control input for operation from compatible mains-voltage control circuits.
• 24–280 V AC load switching range for single-phase industrial equipment.
• Zero-cross switching technology helps reduce switching disturbances with suitable electrical loads.
• Silent semiconductor operation eliminates the mechanical clicking of conventional relays.
• No moving switching contacts means no mechanical contact bounce or contact wear.
• High switching endurance supports frequent switching in automated machinery.
• Single normally open equivalent output simplifies integration into AC control circuits.
• Compact hockey puck-style housing provides a robust industrial switching solution.
• Panel or heatsink mounting supports effective thermal management.
• Screw terminals with folding protective covers provide secure electrical connections.
• IP20 protection rating for installation inside appropriately protected electrical enclosures.
• Suitable for industrial heating, lighting, solenoid and contactor control applications within the relevant electrical ratings.

Key Features

• Finder 77 Series industrial solid state relay.
• Type 77.D1 single-phase semiconductor switching device.
• 60 A rated load current.
• 230 V AC nominal load voltage class.
• 24–280 V AC operating load voltage range.
• 90–280 V AC control voltage range.
• Zero-cross turn-on switching.
• One normally open equivalent output (1 NO / SPST-NO).
• Single-phase AC load switching.
• Silent, spark-free and contact bounce-free switching.
• Hockey puck-style industrial housing.
• Relay-style terminal arrangement with input and output terminals on opposite sides.
• Screw terminal connections.
• Folding protective terminal covers.
• Panel or heatsink mounting.
• IP20 protection rating.
• Operating ambient temperature range of −30 to +80 °C, subject to load current derating.
• CE, UKCA, cURus and EAC compliance markings.

Reliable Zero-Cross Solid State Switching for Industrial Automation

The Finder 77.D1.8.230.8250 uses semiconductor technology to switch AC electrical loads without mechanically operated contacts. When a compatible AC control voltage is applied, the internal switching circuit activates the output, allowing current to flow through the connected load. Removing the control signal causes the device to cease conduction according to the characteristics of the AC waveform and load circuit.

Unlike conventional electromagnetic relays and contactors, a solid state relay has no moving switching contacts. This eliminates mechanical contact bounce and audible switching noise, making the Finder 77.D1.8.230.8250 particularly suitable for applications requiring frequent operation. The absence of mechanical contact wear can also reduce maintenance associated with repeated switching cycles.

A key feature of this model is its zero-cross switching technology. Rather than deliberately activating at an arbitrary point in the AC waveform, the relay switches on when the voltage approaches zero. This helps reduce certain switching transients and electromagnetic disturbances, particularly when controlling resistive loads such as electric heaters.

The 90–280 V AC control input range allows the relay to be operated by compatible AC control circuits. This distinguishes it from solid state relays designed for low-voltage DC control signals. It is therefore suitable for machinery and control panels where an AC control supply is already available.

Its 24–280 V AC load voltage range and 60 A rated output current make the device suitable for a variety of single-phase industrial switching duties. Common examples include resistive heating elements, industrial ovens, lighting equipment and suitable solenoid or contactor control circuits. Load characteristics, inrush current and the manufacturer's switching limits must be considered when selecting the relay.

Correct heatsink selection is essential. Solid state relays generate heat during conduction, and the amount of heat increases with load current. Although the Finder 77.D1.8.230.8250 has a nominal current rating of 60 A, the permissible continuous current depends on the heatsink thermal resistance, ambient temperature, enclosure ventilation and mounting conditions. A suitable heatsink and thermal interface should be selected using the manufacturer's thermal derating guidance.

The relay's hockey puck-style housing is designed for mounting onto a suitable metal surface or heatsink. Its relay-style terminal arrangement separates the control input connections from the AC load terminals, while screw connections and folding protective covers support practical installation in industrial electrical panels.

As with other semiconductor switching devices, the Finder 77.D1.8.230.8250 has a small off-state leakage current. Its output must therefore not be treated as a safety isolation device. A suitable mechanical isolator or disconnecting device must be provided where complete electrical isolation is required for maintenance or safety.

The Finder 77.D1.8.230.8250 is designed for AC load switching. It is not suitable for switching DC loads, and it should not be used as a direct substitute for a mechanical contactor without checking the application's switching characteristics, protection requirements and thermal conditions.

Typical Applications

• Industrial electric heater switching.
• Industrial ovens and process heating equipment.
• Temperature control systems and heating panels.
• Single-phase resistive load switching.
• Industrial lighting control circuits.
• Suitable solenoid and contactor driver applications.
• High-frequency switching in automated machinery.
• Manufacturing and production line equipment.
• Packaging and processing machinery.
• Industrial electrical control cabinets.
• AC control systems requiring silent operation.
• Building services and electrical heating control.
• OEM machinery and industrial automation equipment.
• Applications requiring mains-voltage AC control of high-current AC loads.