Why Choose the Finder 77.01.9.024.8051 Solid State Relay?
The Finder 77.01.9.024.8051 is a compact 5 A solid state relay (SSR) designed for fast, contactless switching of single-phase AC electrical loads. Part of the Finder Series 77 modular solid state relay range, this industrial switching device combines a 24 V DC nominal control input, a 48–265 V AC output switching range and random turn-on technology in a slim DIN rail mounted housing.
Unlike zero-crossing solid state relays, the Finder 77.01.9.024.8051 uses random turn-on switching, allowing the output to begin conducting without waiting for the next AC voltage zero crossing. This makes it particularly useful for applications requiring fast switching response, including certain motor control arrangements, phase-angle control systems and industrial automation circuits.
Featuring a 4–32 V DC operating input range, a 5 A rated AC output and a 17.5 mm wide modular housing, this photo-coupled semiconductor relay provides a practical alternative to conventional electromechanical relays. Its silent operation, lack of moving power contacts and straightforward DIN rail installation make it suitable for industrial machinery, building automation and electrical control panels.
Key Advantages
- 5 A solid state relay for reliable single-phase AC load switching.
- Random turn-on switching for applications requiring fast output activation.
- 24 V DC nominal control input for compatible industrial automation systems.
- 4–32 V DC input operating range for flexible electronic control.
- 48–265 V AC output switching range for suitable AC electrical loads.
- Contactless semiconductor operation eliminates mechanical contact wear and contact bounce.
- Silent switching for noise-sensitive industrial and building automation installations.
- Photo-coupled input and output circuits provide electrical separation between the control and load sides.
- 300 A maximum peak current for 10 ms under specified conditions.
- 17.5 mm slimline housing helps conserve space inside electrical cabinets.
- 35 mm DIN rail mounting for convenient industrial installation.
- Screw terminal connections for practical electrical wiring.
- IP20 protection rating for installation within appropriately protected enclosures.
- Suitable for motor control, industrial automation, heating systems and electronic AC load switching.
Key Features
- Finder Series 77 modular solid state relay.
- Single-phase AC output switching.
- Output configuration: 1 normally open equivalent (SPST-NO / 1 Form A).
- Nominal control voltage: 24 V DC.
- Control input operating range: 4–32 V DC.
- Rated output current: 5 A.
- Output switching voltage: 48–265 V AC.
- Switching characteristic: Random turn-on.
- Maximum peak current: 300 A for 10 ms.
- Minimum switching current: 100 mA under specified conditions.
- Photo-coupled semiconductor switching without moving power contacts.
- Input-to-output impulse insulation: 5 kV (1.2/50 µs).
- Housing width: 17.5 mm.
- Mounting: 35 mm DIN rail.
- Connection type: Screw terminals.
- Operating temperature: −20 to +70 °C.
- Protection rating: IP20.
- Silent, spark-free and bounce-free switching during normal operation.
- Suitable for fast AC load switching and compatible phase-control applications.
Technical Specifications
- Manufacturer: Finder
- Series: 77
- Manufacturer part number: 77.01.9.024.8051
- Product type: Modular solid state relay (SSR)
- Relay technology: Photo-coupled semiconductor
- Output contact equivalent: SPST-NO (1 Form A)
- Number of output poles: 1
- Nominal input voltage: 24 V DC
- Input operating voltage range: 4–32 V DC
- Input supply type: DC
- Output type: AC
- Output voltage range: 48–265 V AC
- Rated output current: 5 A
- Minimum switching current: 100 mA
- Switching method: Random turn-on
- Maximum peak current: 300 A for 10 ms
- Input-to-output impulse insulation: 5 kV (1.2/50 µs)
- Housing width: 17.5 mm
- Mounting type: 35 mm DIN rail (EN 60715)
- Connection type: Screw terminals
- Operating temperature: −20 to +70 °C
- Protection rating: IP20
- Switching operation: Contactless semiconductor switching
- Listed approvals: CE, cULus, EAC and UKCA
- EAN / GTIN: 8012823446745
Fast Random Turn-On Switching for Industrial AC Control
The Finder 77.01.9.024.8051 uses a photo-coupled semiconductor switching mechanism to control an AC electrical load from a low-voltage DC signal. When a compatible control voltage is applied within the 4–32 V DC input range, the relay can activate its output without waiting for the next AC voltage zero crossing. This random turn-on characteristic provides greater flexibility for applications requiring rapid switching response or control at selected points in an AC waveform.
Random turn-on switching is particularly useful in certain motor control, phase-angle control and industrial automation applications. Unlike a zero-crossing relay, which delays activation until the AC voltage approaches zero, a random turn-on relay can respond at different points in the waveform. This behaviour can be beneficial when used with suitable electronic controllers, although the connected load and switching method must be carefully assessed.
The Finder 77.01.9.024.8051 provides a 5 A rated output over a 48–265 V AC switching range. It also has a specified 300 A peak current capability for 10 ms, which describes short-duration surge withstand rather than continuous current capacity. Loads with significant inrush current, including motors, transformers and some lighting equipment, require particular attention to surge ratings and thermal performance.
Because the device uses solid state switching technology, it operates without mechanical contacts, contact bounce or the audible clicking associated with conventional electromechanical relays. This makes it suitable for installations where silent switching and frequent operation are desirable. However, semiconductor switching devices generate heat during conduction, and the permissible load current may depend on ambient temperature and installation conditions.
The relay is housed in a compact 17.5 mm wide DIN rail module with screw terminal connections, allowing convenient integration into industrial electrical cabinets. The input and output circuits are electrically separated through the relay's photo-coupled design, supporting control from compatible low-voltage automation equipment.
As with other solid state relays, the Finder 77.01.9.024.8051 may allow a small leakage current when switched off. It does not provide the physical contact separation required for safety isolation and must not be used as the sole means of isolating equipment for maintenance. Appropriate circuit protection, thermal management and mechanical isolation must be provided where required.
Typical Applications
- Fast single-phase AC electrical load switching.
- Industrial motor control within suitable electrical ratings.
- Phase-angle control systems using compatible electronic controllers.
- Industrial machinery and automated production equipment.
- Heating element and temperature control systems.
- PLC-controlled AC switching through compatible DC outputs.
- Building automation and electrical control panels.
- Industrial process control systems.
- Solenoid and contactor coil control.
- Electronic switching systems requiring random turn-on operation.
- OEM machinery requiring silent semiconductor switching.
- DIN rail mounted industrial control cabinet installations.
