Picking a motor is not just about horsepower. Here's what to consider.
Determine the door's weight. The motor needs to lift it. The weight depends on material, size, and construction. A 12 square meter steel door weighs about 300 to 400 kg. An aluminum door of the same size weighs about 150 to 200 kg. An inorganic fabric fire shutter weighs about 60 to 80 kg. This is the starting point.
Calculate the required torque. The motor doesn't lift the full weight directly. The shaft and barrel provide mechanical advantage. The required motor torque equals the door weight multiplied by the barrel radius, divided by the gear ratio. This calculation should be done by the door manufacturer. If you're replacing a motor, match or slightly exceed the original motor's torque rating.
Consider the duty cycle. How often does the door move? A residential garage door might cycle 4 times a day. A storefront door might cycle 20 times a day. A warehouse high-speed door might cycle 200 times a day. Motors have different duty cycle ratings. Using a residential-duty motor in a commercial application will burn it out quickly.
Choose the voltage. 220V single-phase is standard for most applications. 380V three-phase for larger motors, typically above 2.2 kW. Make sure your facility has the right power available before ordering the motor.
Electrical protection rating. For indoor use, IP44 is adequate. For outdoor use or wet environments, you need IP54 or IP55. The motor housing must seal out water and dust. A motor that's not adequately protected will fail from moisture ingress.
Brake type. Does the motor have an electromagnetic brake that holds the door when power is off? Some motors use a mechanical brake in the gearbox. Electromagnetic brakes are quieter and hold more consistently, but they require the brake to be powered to release.
Thermal protection. The motor should have a thermal cutout that shuts it down if it overheats. Without this, a jammed door can cause the motor to overheat and burn out. Auto-reset thermal protectors are common, but manual-reset types are safer because they force someone to investigate why it tripped.
Noise. In residential applications, motor noise matters. DC motors are quieter than AC motors. Belt-drive openers are quieter than chain-drive. If the garage is under a bedroom, spend the extra money for a quiet motor. Your sleep is worth it.
Brand: For critical applications, go with a brand you trust. A motor failure on a fire shutter during a fire is catastrophic. A motor failure on a warehouse door that stops operations costs money every minute. Don't cheap out on the motor.