901 PHT 24 40 420 AL5, Unison Scr, Input 4-20ma, output 240vac, 40amp

Product Description

The Unison 901 PHT 24 40 420 AL5 is a 40 Amp Analog SCR Power Controller (Phase Angle Controller) designed for precise control of AC power in industrial heating and process control applications. Unlike a standard ON/OFF Solid State Relay, this SCR controller uses phase angle firing to proportionally regulate the power delivered to the load, enabling smooth and accurate temperature control while reducing power fluctuations and improving process stability. It is ideal for applications where variable power output is required rather than simple switching.

The controller accepts a 4–20 mA analog input signal, making it directly compatible with PLC analog output modules, PID temperature controllers, DCS systems, and industrial automation controllers. It controls 230/240 VAC single-phase loads up to 40 Amps, making it suitable for electric heaters, infrared heaters, ovens, furnaces, dryers, and other resistive heating applications. The AL5 aluminium base plate ensures efficient heat transfer to an external heat sink for reliable long-term operation.

The 901 PHT 24 40 420 AL5 incorporates back-to-back SCR technology, providing smooth linear power control across the entire input range. It features 6 kV input-to-output isolation, 4 kV body insulation, and built-in 2700 Vrms surge protection to safeguard both the controller and connected equipment against electrical disturbances. The relay is housed in a compact 45 mm industrial housing with DIN rail compatibility, making installation simple in electrical control panels.

This SCR power controller is widely used in plastic processing machines, industrial ovens, packaging equipment, textile machinery, food processing systems, and laboratory heating equipment where accurate temperature regulation improves product quality and energy efficiency.

For reliable operation at higher currents, the controller should be installed with the recommended G-68 heat sink or an equivalent cooling arrangement.

Key Features

• Model: 901 PHT 24 40 420 AL5
• Brand: Unison
• Analog SCR Power Controller
• Phase Angle Control
• Rated Current: 40 Amp
• Input Signal: 4–20 mA
• Output Voltage: 230/240 VAC
• Back-to-back SCR technology
• Smooth proportional power control
• Built-in surge voltage protection
• 6 kV input-to-output isolation
• DIN rail compatible
• Compact 45 mm industrial housing

Technical Specifications

Applications

The Unison 901 PHT 24 40 420 AL5 is suitable for:

• PID temperature control systems
• Electric resistance heaters
• Industrial ovens and furnaces
• Infrared heater control
• Plastic extrusion and injection moulding machines
• Packaging and sealing machines
• Textile processing equipment
• Food processing machinery
• Drying ovens
• Laboratory heating equipment

Why Buy from Voltkart?

• Genuine Unison SCR Power Controllers
• GST Invoice provided
• Pan India delivery
• Bulk pricing for OEMs, machine builders, and panel manufacturers
• Expert technical support for product selection
• Trusted supplier of industrial automation products

Frequently Asked Questions

1. What is the difference between this SCR controller and a standard SSR?

A standard SSR provides ON/OFF switching, whereas the 901 PHT 24 40 420 AL5 uses phase angle control to proportionally regulate power, making it ideal for accurate temperature and heater control.

2. Which control signal does this SCR accept?

This model accepts a 4–20 mA analog input, allowing direct connection to PID controllers, PLC analog outputs, and DCS systems.

3. Is a heat sink required?

Yes. For continuous operation at higher loads, Unison recommends using the G-68 heat sink to ensure proper heat dissipation and reliable long-term performance.

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