Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 526

Glossary
Qualified user
A qualified user is a properly trained individual who is familiar with the construction and
operation of the equipment and the hazards involved.
RAM
RAM is an acronym for Random Access Memory, a temporary storage area for drive information.
The information in RAM is lost when power is no longer supplied to it. Therefore, it is referred to
as volatile memory.
Regeneration
Regeneration is the characteristic of an AC motor to act as a generator when the rotor's
mechanical frequency is greater than the applied electrical frequency.
Relay
A relay is an electrically controlled device that causes electrical contacts to change their status.
Open contacts will close and closed contacts will open when rated voltage is applied to the coil
of a relay.
RS232C
RS232C is a serial communications standard of the Electronics Industries Association (EIA).
Set point
Set point is the desired or optimal speed of the VFD to maintain process levels (speed command).
Slip
Slip is the difference between the stator electrical frequency of the motor and the rotor
mechanical frequency of the motor, normalized to the stator frequency as shown in the
following equation:
Slip = (ωS - ωR) / ωS
Slip compensation
Slip compensation is a method of increasing the speed reference to the speed regulator circuit
(based on the motor torque) to maintain motor speed as the load on the motor changes. The slip
compensation circuit increases the frequency at which the inverter section is controlled to
compensate for decreased speed due to load droop. For example, a motor with a full load speed
of 1760 rpm has a slip of 40 rpm. The no load rpm would be 1800 rpm. If the motor nameplate
current is 100 A, the drive is sending a 60 Hz wave form to the motor (fully loaded); then the slip
compensation circuit would cause the inverter to run 1.33 Hz faster to allow the motor to
operate at 1800 rpm, which is the synchronous speed of the motor.
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NXGPro+ Control Manual
Operating Manual, A5E50491925A