Finder 77.H1.8.230.8650 – 77 Series Modular solid state relays

Why Choose the Finder 77.H1.8.230.8650 Solid State Relay?

The Finder 77.H1.8.230.8650 is a high-power 125 A single-phase solid state relay (SSR) designed for reliable, silent switching of AC electrical loads in industrial automation, electric heating and machinery control applications. Part of the Finder 77 Series, this industrial semiconductor relay provides a robust alternative to conventional electromagnetic switching devices where high current capacity, frequent operation and minimal mechanical maintenance are important.

Featuring a 90–280 V AC control input and a 24–660 V AC load switching range, the Finder 77.H1.8.230.8650 enables compatible mains-voltage control circuits to operate high-power AC equipment. Its zero-cross turn-on technology activates the semiconductor output near the AC voltage zero crossing, helping reduce switching-related electrical disturbances when controlling suitable resistive loads.

With a 125 A rated output current, 2,250 A maximum non-repetitive peak current for 10 ms and a compact hockey puck-style housing, this Finder solid state relay is designed for demanding industrial installations. Its screw terminals, protective folding covers and panel or heatsink mounting arrangement make it particularly suitable for industrial ovens, electric heating systems, process machinery and electrical control panels. Appropriate thermal management is essential to achieve the required operating performance.

Key Advantages

• 125 A rated output current for demanding high-power AC switching applications, subject to appropriate heatsinking and thermal derating.
• 24–660 V AC operating load range supports a wide variety of industrial AC equipment.
• 90–280 V AC control input enables operation from compatible mains-voltage control circuits.
• Zero-cross turn-on switching helps minimise switching disturbances with suitable resistive loads.
• 2,250 A maximum non-repetitive peak current for 10 ms provides a substantial short-duration surge capability under specified conditions.
• Silent semiconductor operation eliminates the mechanical clicking associated with conventional relays and contactors.
• No moving switching contacts means no mechanical contact bounce or contact erosion.
• High switching endurance supports frequent operation in automated production and process control systems.
• Single normally open equivalent output provides straightforward integration into AC load circuits.
• Low-power electronic control allows high-current load switching without an electromagnetic operating coil.
• Compact hockey puck-style housing supports installation in industrial control cabinets.
• Panel or heatsink mounting allows the thermal management arrangement to be selected for the application.
• Folding protective terminal covers help protect electrical connection points.
• IP20 protection rating for installation within appropriately protected electrical enclosures.
• Suitable for industrial heater control, electric ovens, lighting equipment and automated machinery.

Key Features

• Finder 77 Series industrial solid state relay.
• Type 77.H1 high-current single-phase semiconductor switching device.
• 125 A rated load current.
• 600 V AC rated output voltage.
• 24–660 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.
• 47–400 Hz load operating frequency.
• 2,250 A maximum non-repetitive peak current for 10 ms.
• 1,600 V peak repetitive blocking voltage.
• 0.1 mA off-state leakage current at rated voltage.
• 4 kV input-to-output dielectric withstand voltage.
• LED operating status indication.
• Hockey puck-style industrial housing.
• Relay-style terminal arrangement with control and load connections on opposite sides.
• Screw terminals with folding protective covers.
• Panel or heatsink mounting.
• IP20 protection rating.
• Operating ambient temperature range of −30 to +80 °C, subject to current derating.

High-Current Zero-Cross Switching for Industrial Heating and Automation

The Finder 77.H1.8.230.8650 uses semiconductor switching technology to control high-current AC electrical loads without mechanically operated contacts. When the appropriate AC control voltage is applied, the internal switching circuit enables the output to conduct. Removing the control signal causes the output to stop conducting when the electrical conditions permit, typically at a subsequent AC current zero crossing.

Unlike a conventional electromagnetic contactor, the relay has no moving switching contacts. This eliminates mechanical contact bounce and audible switching noise, making it particularly useful in automated machinery and heating systems requiring frequent switching. The absence of mechanical contact wear can also reduce maintenance associated with repeated switching operations.

A defining feature of this model is its zero-cross turn-on switching technology. Instead of deliberately activating at an arbitrary point in the AC waveform, the relay begins conduction near the voltage zero crossing. This helps reduce certain switching transients and electromagnetic disturbances, particularly when switching resistive heating elements and other suitable AC loads.

The 90–280 V AC control input enables the Finder 77.H1.8.230.8650 to operate from compatible mains-voltage control circuits. Its nominal control voltage is 230 V AC, making it suitable for industrial installations using this control supply. The device is not intended for direct operation from a standard 24 V DC PLC transistor output; a suitable interface or different SSR input variant would be required.

With a 24–660 V AC load voltage range and 125 A rated output current, this relay can switch appropriately rated high-power AC equipment. Applications include industrial heating elements, electric ovens, process heaters, lighting systems and selected automation loads. The connected equipment must be evaluated against the manufacturer's current, voltage, frequency and load-specific switching limits.

The relay also provides a substantial 2,250 A non-repetitive peak current capability for 10 ms. This is a short-duration surge withstand specification and must not be interpreted as a continuous operating current or a guarantee of compatibility with every high-inrush load. Suitable semiconductor protection and coordination with the connected equipment remain essential.

Thermal management is especially important for this 125 A model. Solid state relays generate heat while conducting, and the Finder 77.H1.8.230.8650 has a specified power dissipation of approximately 150 W at rated current. A correctly selected heatsink, suitable thermal interface and adequate enclosure ventilation are necessary to prevent overheating. The manufacturer's thermal derating information should be used to determine the permissible continuous current for the actual installation.

The hockey puck-style housing is designed for installation on a suitable heatsink or metal control cabinet mounting surface. Its relay-style terminal arrangement places the control and load connections on opposite sides, helping simplify wiring in industrial panels. Screw terminals and folding protective covers provide practical connection and terminal protection features.

The integrated LED status indication assists with commissioning and fault-finding by providing a visual indication of the relay's operating state. However, an illuminated or extinguished indicator must not be used as proof that the load circuit is electrically isolated.

As with other semiconductor switching devices, the Finder 77.H1.8.230.8650 exhibits a small off-state leakage current. Its output therefore does not provide the same physical isolation as an open mechanical contact. Suitable mechanical isolation, overcurrent protection and appropriately rated semiconductor protection must be incorporated into the electrical installation.

Typical Applications

• High-power industrial electric heater switching.
• Industrial furnaces and electric ovens.
• Process heating and temperature control equipment.
• Large resistive heating element control.
• Industrial drying and curing systems.
• High-current single-phase AC load switching.
• Industrial lighting control systems.
• Suitable solenoid and contactor driver circuits.
• Automated production and manufacturing equipment.
• Packaging, bottling and labelling machinery.
• Industrial process control panels.
• Electrical heating control cabinets.
• High-frequency switching applications requiring silent operation.
• OEM industrial machinery and electrical panel manufacturing.
• Industrial automation systems using 230 V AC control signals.