Synchronous
The running of the rotor at the same speed as the stator field which is determined by the frequency of the supply.

Synchronous speed
Constant speed of rotation at constant frequency based upon the number of pole pairs of the motor.



f = frequency (Hz), n = speed (rpm) p = number of pole pairs

Synchronous torque
Torque which the motor is still capable of producing without falling out of synchronism, once the synchronous speed of rotation has been reached.

Starting torque
Load torque the motor is capable to start. It is influenced by the type and manner of coupling to the load, the load inertia, the gearbox design and the supply voltage. In the case of a very large reduction ratio a small external moment of inertia and nominal gearbox play the starting torque becomes equal to the synchronous torque.

Detent torque (static)
Defines the maximum torque which can be applied to a deenergised motor without causing the motor to rotate. Catalogue specifications refer to the static detent torque.

Detent torque (dynamic)
Defines the maximum torque at which the motor comes to an immediate standstill from synchronous running when the excitation current is switched off.

Permissible load inertia
Is the maximum inertia load the motor can start without external help.

Stall-proof
Synchronous motors with permanent magnet rotors can be stalled without damage to the motor winding.

Torque limit (Torque limited motors)
The constant torque produced by the hysteresis- magnetic clutch within the torque limited synchronous motor in the stalled condition.

Design characteristics
The basic design is the same as for our stepper motors, but the motors are operated by a sinus waveform voltage.

ED or Duty Cycle
Duty cycle of operation, based on a cycle time of 5 minutes (1 minute for URG) and a frequency f=0Hz; e.g. ED=30% means that the motor can be continuously powered 1.5 minutes (30% of 5 minutes) without overheating.

Step
Rotary movement of the rotor through one step angle.

Step angle
Rotary angle through which the motor shaft turns per controlled pulse.

Stepping frequency
Number of steps of the stepping motor in 1 sec.

Driver
Electronics which convert step and direction input signals to high power currents and voltages to drive a step motor.

Unipolar driver
Unipolar means that every coil end has one polarity only. A unipolar coil consists in fact of 2 coils. Alternating the current flows through one of these coils and in one direction.
Compared to a bipolar motor only half of the copper is used at time.
The motor phase winding must be center tapped. On the SAMOTRONIC101 this is already fixed on the board.

Often an additional Zener diode is used to ensure a fast current decay in the switched-off coil. This will give an increased motor torque especially at higher frequencies.Torque graphs in this catalogue are measured with a 10V Zener diode.

Bipolar Driver
Bipolar indicates that every coil end is bipolar, during driving it will be „+“ as well as „-“.Since every coil is fully used the motor has a higher torque compared to a unipolar one.Very often a bipolar driver has a constant current drive capability (also called chopper). That will give an increased torque output on higher frequencies and a lower influence of temperature and supply voltage variations. Typical applications use the SAMOTRONIC102.

Rotational speed
Revolutions of the motor per minute calculated from:



f = stepping frequency, α = step angle.

Detent torque (static)
Defines the maximum torque which can be applied to a deenergised motor without causing the motor to rotate. Catalogue specifications refer to the static detent torque.

Holding torque
Defines the maximum torque with which an energized motor can be loaded without giving rise to a continuous rotary movement.

Pull-in torque
Operation torque when switching on step frequency at once, without a ramp.

Pull-out torque
Operation torque when applying an acceleration / deceleration ramp.

Load inertia moment
The sum of all the mass inertia moments occurring on the shaft of the stepping motor.

Steps/rev
The number of steps per 360° rotation.

Maximum operating torque
The maximum torque which a stepper motor without external mass inertia can generate without stepping losses.