Transformer fan speed controller for single-phase motors. The (combined) maximum current is 5 Amps. AC fan speed is regulated from low to high in 5 steps and can be selected via the rotary switch. This rotary switch also has an OFF position. The motor speed is regulated in 5 steps by varying the motor voltage. The output voltage with perfect sinusoidal shape, guarantees quiet motor operation. The enclosure offers an IP54 protection against ingress of dirt, dust and moisture. It can be wall mounted in indoor environments. This 5-step speed controller is often used to control cooker hood extractor fans, ceiling fans, exhaust fans, etc.