Glossary

Motor Housing Assembly (stator)

Metal Housing - A metal case to house the magnets and bearings and fix the endcap. It is also responsible for producing a magnetic field using the magnets to chart the flow of magnetic force.

Bearing - This component supports the shaft that is part of the armature assembly and also provides lubrication for the shaft to turn with less friction.

Magnet - The permanent magnet is the key component in producing a magnetic field which in turn produces torque or the turning force of the motor.

Spring Holder - This component fixes the magnet to the housing


Armature Assembly (rotor)

Commutator - The commutator commonly uses copper segments and more recently, graphite. This component comes in contact with the brush to allow curreont to flw through the armature and is responsible for the direction of the current to shift as it spins and slides in contact with the brushes.

Lamination Stack - Composed of stamped sheet metal called laminations, the lamination stack has slots for the magnet wire windings where current can flow.

Magnet Wire - Magnet wires are used as windings for the armature. d. Shaft - The shaft is where the mechanical output characteristics of the motor are measured such as speed and torque. The whole idea of the motor is to provide rotational motion to the shaft.


Endcap Assembly

Brush Holder - This component holds the brush in place and provides electrical insulation from the metal housing.

Endcap - The endcap is a stampedmetal part that holds the bearing in place and strengthens the plastic brush holder. The terminals protrude through the endcap.

Terminals - Usually in pairs, the terminals are the electrical input contacts of the motor.

Brush - The brush, usually composed of carbon material, enables electrical current to flow from the terminal to the armature as it slides in contact with the commutator while the armature assembly is rotating.

Brush Leaf - This component holds the brush and enables the brush to slide and come in contact with the commutator at just the right amount pressure.

Power consumption Pin
The power consumption expressed in W was determined in no-load operation

Load
The total sum of all static and dynamic torques (e.g. friction torque, mass inertia, acting on the rotor).

Speed n
RPM revolution per minute

Torque
The running torque in cNm (also synchronous, braking or dynamic torque) defines the load at which the synchronous motor falls out of synchronism and stalls.

Power output
The power output expressed in W is determined according to the following formula:

 
Md in Nm (1 cNm = 0.01 Nm), n in rpm

Pole pair number
The number of rotor pole pairs North/South.

Direction of rotation
This information always refers to the output shaft, either of the motor or of the gearbox.
Right = clockwise rotation (CW),
Left = counterclockwise rotation (CCW)

Gear torque
The maximum gear torque in cNm defines the maximum load for a required life of at least 1000 operating hours

Running time
This value refers to the time (t) per revolu- tion (U); they are calculated using the following formula:

 
i = transmission ratio n = motor speed

Axial thrust / lateral force / lateral torque
These values refer to the loads on the standard output shaft of the respective gear.

The permissible lateral torque referring to the standard shaft must not be exceeded on special shafts either.

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 fre- quency based upon the number of pole pairs of the motor

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

Synchronous 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 tor- que becomes equal to the synchronous torque.

Detent torque (static)
Defines the maximum torque which can be applied to a deenergized 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.


General technical terms relating to the stepper motor

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 minu- tes) 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 cur- rent drive capability (also called chopper). That will give an increased torque output on higher frequencies and a lower influence of tempera- ture 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 deenergized 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 accelera- tion / deceleration ramp.

Load inertia moment
The sum of all the mass inertia moments oc- curring 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 mo- tor without external mass inertia can generate without stepping losses.