Finder 77.E2.9.024.8671 – 77 Series Modular solid state relays

Why Choose the Finder 77.E2.9.024.8671 Two-Phase Solid State Relay?

The Finder 77.E2.9.024.8671 is a high-current 75 A two-phase solid state relay (SSR) designed for reliable, silent and contactless switching in industrial automation, electric heating systems and machinery control. Part of the Finder Series 77, this industrial relay combines two independent semiconductor switching channels with a robust hockey puck-style housing.

Featuring a 600 V AC rated output voltage and a 24–660 V AC switching range, the Finder 77.E2.9.024.8671 provides two independently controlled normally open outputs (2 NO / DPST-NO), each rated for 75 A under the specified operating and thermal conditions.

Each output channel is operated by its own 4–32 V DC control input, with a nominal control voltage of 24 V DC. The relay uses random turn-on switching, also known as instantaneous switching, making it suitable for applications requiring rapid electronic switching rather than zero-crossing activation.

Its panel-mounting construction, screw terminals, folding protective terminal covers and heat sink-compatible design make the Finder 77.E2.9.024.8671 a practical solution for professional industrial electrical installations.

Key Advantages

• Two independent switching channels: Allows separate control of two AC electrical loads or phases.
• 75 A rated current per channel: Provides high-current switching capability when correctly installed and cooled.
• 24–660 V AC switching range: Supports a broad range of industrial AC applications.
• 24 V DC nominal control voltage: Suitable for integration with compatible industrial control equipment.
• 4–32 V DC control input range: Offers flexibility for low-voltage electronic control circuits.
• Random turn-on switching: Provides rapid semiconductor activation without waiting for an AC voltage zero crossing.
• 750 A peak current capability: Supports short-duration current surges of up to 750 A for 10 ms under specified conditions.
• Silent operation: Eliminates the mechanical clicking associated with conventional relays and contactors.
• Contact bounce-free switching: Avoids mechanical contact movement and associated wear.
• High switching endurance: Designed for frequent operation in industrial control systems.
• Hockey puck-style construction: Suitable for mounting on control cabinet sheet metal or a dedicated heat sink.
• Contactor-style terminal arrangement: Supports organised wiring within industrial control panels.

Key Features

• Finder Series 77 industrial solid state relay.
• Type 77.E2 dual-channel configuration.
• Two independent normally open semiconductor outputs.
• 2 NO / DPST-NO output arrangement.
• 75 A rated output current per channel.
• 600 V AC rated output voltage.
• 24–660 V AC switching voltage range.
• 24 V DC nominal control input.
• 4–32 V DC control voltage operating range.
• Independent low-power DC control inputs.
• Random or instantaneous turn-on switching.
• 47–400 Hz operating frequency range.
• 750 A maximum peak current for 10 ms.
• 1200 V repetitive peak OFF-state voltage.
• 15 A AC-53 rated load current.
• Silent, spark-free and contact bounce-free switching.
• High switching speed and electrical endurance.
• Hockey puck-style housing with folding screw covers.
• Panel or heat sink mounting.
• Screw terminals with plate-clamp connections.

Independent Two-Phase Switching for Industrial Control

The Finder 77.E2.9.024.8671 features two independent semiconductor output channels, each controlled by a separate low-voltage DC input. This arrangement allows two AC loads or phases to be switched independently, providing greater control flexibility than a conventional single-channel solid state relay.

Each channel supports a 75 A rated output current and operates within a 24–660 V AC switching range. The relay is designed for industrial applications where high-current AC loads must be controlled electronically, particularly heating equipment and suitable motor-control circuits.

The relay uses random turn-on switching, meaning that the output activates in response to the control signal without deliberately waiting for the AC waveform to reach its zero-crossing point. This provides a fast switching response and can be advantageous in control applications requiring short operating times.

With a typical 1 ms operate time and 10 ms release time, the Finder 77.E2.9.024.8671 is suitable for industrial control systems requiring rapid electronic switching. Its contactless design eliminates mechanical contact bounce and reduces wear associated with repeated switching operations.

The relay's 47–400 Hz operating frequency range extends its potential use beyond conventional 50/60 Hz mains supplies, provided the electrical system and connected loads remain within the specified operating limits.

Thermal Management and Installation Requirements

High-current solid state relays generate heat during operation because their semiconductor outputs exhibit an ON-state voltage drop. The Finder 77.E2.9.024.8671 has a specified 180 W power loss at rated current, making correct thermal management an essential part of the installation.

The relay is designed for mounting on control cabinet sheet metal or a suitable heat sink. Finder's thermal performance information references a 0.45 K/W heat sink for the 77.E2 configuration, although the actual allowable current depends on ambient temperature, heat sink performance and installation conditions.

When operating near its rated current, installers should ensure adequate heat transfer, suitable mounting arrangements and sufficient ventilation. The relay's current-carrying capability must be checked against the manufacturer's thermal derating information.

The device also provides a specified 15 A AC-53 utilisation rating, which is relevant when assessing motor and other demanding load applications. The general 75 A current rating must not be assumed to apply to all load types.

As with other solid state relays, a small leakage current can flow when the output is switched off. This relay must therefore not be used as a substitute for a mechanical isolator. Appropriate overcurrent protection and a separate means of electrical isolation should be provided where required.

Typical Applications

• Two-phase industrial electrical load switching.
• Industrial electric heating systems.
• Resistive heating element control.
• Industrial ovens and furnaces.
• Temperature-controlled manufacturing equipment.
• Industrial motor-control applications within the applicable utilisation rating.
• PLC-controlled AC load switching.
• Industrial process automation.
• Packaging and production machinery.
• Manufacturing and assembly equipment.
• Electrical control cabinets and machine panels.
• Applications requiring independently controlled AC switching channels.
• High-frequency switching applications.
• OEM industrial automation and electrical control assemblies.