Technical information

181
Glossary
Dead Band
A range of input signal levels for which there is no system response.
Demag Current
The amount of current at which the motor magnets will be demagnetized. This is an irreversible effect
which will alter the motor characteristics and degrade performance.
Dielectric Test
A high voltage breakdown test of an insulation’s ability to withstand an AC voltage. Test criterion limits the
leakage current to a specified magnitude and frequency, applied between the specified test points.
Digital-to-Analog Converter
A device for converting a digital word into an analog voltage.
Differential Signal
An electrical input or output signal which uses two signal lines where the “difference” in value between the
two lines is significant and not either ones individual value. This is used to minimize the effects of noise and
ground level “float” between transmitters and receivers.
Distributed Processing
A technique to gain increased performance and modularity in control systems utilizing multiple computers
or processors.
Drive, Digital
Usually referring to any type of motor drive in which the tuning or compensation is done digitally. Input
may be an analog or digital signal.
Drive, Linear
A motor drive in which the output power section supplies a pure DC signal proportional to the command.
Normally the inputs are analog signals. This is a very inefficient (50%) drive type requiring a lot of cooling
to operate but generates the smallest output without switching noise.
Drive, PWM
A motor drive utilizing Pulse-Width Modulation techniques to control power to the motor. Typically a high
efficiency drive generates a smooth motor torque but also generates switching noise.
Drive, SCR
A DC motor drive which utilizes internal silicon controlled rectifiers as the power control elements. Very
effective in high power applications. Usually used for low bandwidths, high power applications. Not as
smooth as PWM or linear drives.
Drive, Servo
A motor drive which utilizes feedback and compensation loops for accurate control of motor current or
velocity.
Drive, Stepper
Electronics which convert step and direction inputs to high power currents and voltages to drive a stepping
motor. The stepping motor driver is analogous to the servo motor amplifier.