NEMA and Metric Explosion Proof Stepper Motors
A Step Motor is defined as a device whose normal shaft motion consists of discrete angular movements of essentially uniform magnitude when driven from a sequentially switched DC power supply. A step motor is a digital input-output device. It is particularly well suited to the type of application where control signals appear as digital pulses rather than analog voltages. One digital pulse to a step motor drive or translator causes the motor to increment one precise angle of motion. As the digital pulses increase in frequency, the step movement changes into continuous rotation. There are three basic types of step motors in use. The first is the Active rotor: permanent magnet (PM). THe second is the Reactive rotor: variable reluctance (VR). The third, and most common type in industrial automation is a combination of PM and VR: hybrid (HY).
Design Tips for Using Step Motors:
- Parallel connect the lead wires for best torque over the widest speed range
- If not enough current is available from the drive, series connect the lead wires for full torque at low speeds
- Keep motor case temperature below 100 °C. This can be achieved by lowering the motor current or limiting the duty cycle
- Allow sufficient time to accelerate load
- Use a microstepping drive for smoothest motor performance over a wide speed range
- For open loop operation, size the motor with a 30-50% torque margin at speed. Including an encoder in the system and using a Stall Prevention feature may allow operation all the way down to a 0% torque margin
- Do not disassemble motors. A significant reduction in motor performance will result
- Do not machine shafts without consulting Electromate® first
- Do not disconnect motor from drive while power is applied. Remove power from the drive before disconnecting the motor
- Do not use holding torque/detent torque of motor as fail-safe brake
- Use an Electromate® recommended stepper drive with your step motor to ensure optimal performance
Electromate® sells a family of 2-phase hybrid type step motors with a 1.8° step angle in NEMA frame sizes from NEMA 8 to NEMA 42. Stepper motors from Electromate® are available in 4, 6 or 8 lead configurations for bipolar or unipolar operation. All motors can be wired in series or parallel, depending on the requirement. Motors are available with optional rear shaft extensions, encoders, brakes, cables, gearboxes and IP65 sealing.