VENTS RSA5E-4-M – 5-step single-phase transformer fan controller, 4A

VENTS RSA5E-4-M is a professional 5-step transformer speed controller designed to control single-phase AC fans with a maximum rated current of up to 4 A. The speed is selected using a mechanical rotary switch, while autotransformer control ensures stable and reliable motor operation. The model has built-in motor-overheating protection and can be connected to a thermostat and air-damper actuator.

VENTS RSA5E-4-M is designed to regulate the airflow of compatible single-phase fans by changing the motor speed. Unlike conventional electronic controllers, the model uses a transformer control principle and offers five predefined operating steps.

The desired speed is set using a mechanical rotary switch on the front panel. This makes control easy and allows the airflow to be adapted to the specific needs of the ventilation system – for example, a lower speed under normal conditions and a higher speed when intensive air exchange is needed.

One of the important advantages of the RSA5E-4-M is its integrated motor protection. The controller can operate with the thermal contacts of a compatible fan. If the motor's thermal relay is triggered because of overheating, power to the fan is interrupted. Once conditions return to normal, the power supply is restored automatically.

It also has additional terminals for connecting an external thermostat or air-damper motor, allowing the controller to be integrated into more complex climate-control and ventilation installations.

The RSA5E-4-M has a metal casing and is designed for surface wall mounting. Its protection rating is IP21, and the permitted ambient operating temperature is from +5°C to +40°C.

Technical specifications

✔️ Manufacturer: VENTS
✔️ Model: RSA5E-4-M
✔️ Type: Transformer speed controller
✔️ Control: Stepped
✔️ Number of speeds: 5
✔️ Phases: 1
✔️ Supply voltage: 230 V / 50 Hz
✔️ Rated motor voltage: 230 V / 50 Hz
✔️ Maximum rated load: 4.0 A
✔️ Fuse: 5.0 A
✔️ Protection rating: IP21
✔️ Operating temperature: +5°C to +40°C
✔️ Casing: Metal
✔️ Mounting: Surface wall mounting
✔️ Dimensions: 241 × 184 × 132 mm
✔️ Weight: 4.5 kg
✔️ Terminals: screw type, 0.5–2.5 mm².

🛡️ Functions and protections

RSA5E-4-M offers more than ordinary speed control:

✔️ 5-step adjustment of the fan speed
✔️ Mechanical rotary switch
✔️ Integrated motor overheat protection
✔️ Automatic power restoration after the temperature returns to normal
✔️ Option to connect a thermostat
✔️ Option to control an air-damper actuator.

🔧 Applications

VENTS RSA5E-4-M is suitable for controlling compatible single-phase fans in:

• Greenhouses
• Nurseries
• Warehouses
• Production facilities
• Workshops
• Technical rooms
• Supply ventilation systems
• Extract ventilation systems
• Other professional systems where stepped air-flow control is required.

🔌 Operating principle

When a different position is selected on the rotary switch, the controller supplies a different voltage to the fan motor. In this way, the speed and therefore the air flow change in five distinct stages.

This type of control is particularly suitable for compatible AC motors when reliable adjustment is required without the need for complex electronics.

📋 Installation and use

1. Mount the controller vertically on a stable wall.
2. Connect the power supply and fan to the corresponding terminals according to the VENTS wiring diagram.
3. If the motor has suitable thermal contacts, connect them to the controller's protection circuit.
4. If necessary, connect an external thermostat or air-damper actuator.
5. After checking the electrical installation, switch on the power supply.
6. Select the required speed using the rotary switch.

⚠️ Important: The maximum rated load of the RSA5E-4-M is 4.0 A. Before connection, the fan motor's rated current and its compatibility with transformer control must be checked. Electrical connection should be carried out according to the manufacturer's diagram and requirements.

💡 Tip from Urban Botaniks: A transformer controller is a good choice for ventilation systems where the fan does not need to run constantly at maximum speed. Selecting a suitable lower stage can reduce air flow and noise, while maximum speed remains available for periods when more intensive air exchange is needed.