Finder 77.A1.9.024.8650 – 77 Series Modular solid state relays

Why Choose the Finder 77.A1.9.024.8650 Solid State Relay?

The Finder 77.A1.9.024.8650 is a high-performance single-phase solid state relay (SSR) designed for reliable, silent and contactless switching of AC electrical loads. Part of the Finder 77 Series, this industrial relay uses semiconductor switching technology instead of mechanical contacts, making it particularly suitable for applications requiring frequent switching, reduced maintenance and dependable operation.

Featuring a 3–32 V DC control input, a 25 A rated load current and a 24–660 V AC load switching range, the Finder 77.A1.9.024.8650 provides an effective interface between low-voltage electronic control systems and higher-voltage AC equipment. Its zero-crossing switching function activates the load close to the AC voltage zero crossing, helping reduce electrical interference during switching.

The relay features a compact hockey puck-style housing, screw terminal connections and a protective folding terminal cover. Designed for mounting on a suitable metal panel or heatsink, it is particularly well suited to industrial heating systems, temperature controllers, lighting equipment and automated machinery.

Key Advantages

• 25 A rated load current for suitable industrial AC switching applications.
• 24–660 V AC load voltage range provides flexibility across different AC installations.
• 3–32 V DC control input supports integration with compatible PLC outputs and electronic controllers.
• Zero-crossing switching helps minimise electrical interference when switching suitable AC loads.
• Silent operation eliminates the mechanical clicking associated with conventional electromagnetic relays.
• Contactless semiconductor switching avoids mechanical contact bounce and contact arcing.
• High switching endurance makes the relay suitable for applications involving frequent operating cycles.
• Fast electronic switching supports automated control of compatible AC equipment.
• Compact hockey puck housing provides a practical format for industrial control panel installation.
• Panel or heatsink mounting supports effective thermal management.
• Screw terminals with protective covers provide convenient electrical connections.
• IP20 protection rating for installation within a suitable electrical enclosure.

Key Features

• Finder 77 Series industrial solid state relay.
• Single-phase AC output switching.
• 25 A rated load current.
• 24–660 V AC operating load voltage.
• 3–32 V DC control voltage range.
• Zero-crossing turn-on for suitable AC loads.
• Single normally open equivalent output (1 NO / SPST-NO switching function).
• Electronic semiconductor switching without moving contacts.
• Silent, spark-free and contact-bounce-free operation.
• Suitable for frequent switching applications.
• Low-power DC control interface.
• Hockey puck-style industrial housing.
• Relay-style terminal arrangement with input and output terminals on opposite sides.
• Screw terminal connections.
• Folding protective terminal cover.
• Panel or heatsink mounting.
• IP20 protection rating.
• −30 to +80 °C ambient operating temperature range, subject to thermal derating.
• Suitable for heater control, lighting, solenoid and contactor driving applications where the electrical characteristics are compatible.

Reliable Solid State Switching for Industrial Automation

The Finder 77.A1.9.024.8650 operates by using a low-voltage DC control signal to activate an electronic switching device within the relay. When the control input is energised, the semiconductor output allows current to flow through the connected AC load. When the control signal is removed, the relay switches off according to its electronic switching characteristics.

Unlike a conventional electromechanical relay, the Finder 77.A1.9.024.8650 has no moving output contacts. This provides silent switching, no mechanical contact bounce and reduced wear associated with repeated switching cycles. These characteristics are particularly valuable in temperature control systems where heaters may be switched frequently to maintain a desired process temperature.

Its zero-crossing switching function delays turn-on until the AC supply waveform approaches a zero-voltage crossing. For suitable resistive loads, this helps reduce switching disturbances and electromagnetic interference compared with switching at arbitrary points in the AC waveform.

The relay's 3–32 V DC input also makes it suitable for integration with compatible industrial electronic controllers, PLCs and temperature control equipment. A relatively low-power control signal can therefore be used to switch a higher-voltage AC circuit, provided that the connected load and installation remain within the relay's electrical and thermal ratings.

Thermal Management and Installation Considerations

As with other power semiconductor relays, the Finder 77.A1.9.024.8650 generates heat when conducting load current. Correct thermal management is therefore essential, particularly when operating at higher currents or elevated ambient temperatures.

The relay is designed for mounting on a suitable metal panel or heatsink. The heatsink arrangement, thermal interface, enclosure ventilation and ambient temperature must be considered when determining the permissible continuous load current.

The 25 A rating must not be interpreted as an unconditional continuous-current capability in every installation. The manufacturer's load-current derating information and heatsink requirements should be followed to avoid excessive operating temperatures.

Because solid state relays can exhibit a small leakage current when switched off, the output should not be treated as providing mechanical isolation from the supply. A suitable disconnecting device and appropriate circuit protection must be provided where required.

The relay is intended for AC load switching. Its DC control input does not mean that it is suitable for switching DC loads.

Typical Applications

• Industrial electric heater control.
• Temperature regulation and process heating equipment.
• Heating elements in ovens, dryers and manufacturing machinery.
• Plastic processing and packaging machinery.
• Industrial automation systems requiring frequent AC switching.
• PLC-controlled electrical load switching.
• Electronic temperature controller outputs.
• Commercial and industrial heating equipment.
• Suitable AC lighting control applications.
• Compatible solenoid and contactor driving circuits.
• OEM machine building and industrial control panels.
• Electrical systems requiring quiet, contactless switching.