Table of Contents
Advertisement
GEH-5201, Synchronous-motor Control
SECTION 3 - Description of Synchronous-motor Controllers
3.1 General
Synchronous-motor Control equipment can be supplied
either as a complete controller (including an ac power switching
device for the motor starter) or as a field panel (ac power
switching supplied by others).
3.2 Elements of a complete
synchronous-motor controller
The complete Synchronous-motor Controller has the ability
to switch the motor on to and off of the power system and protect
the motor from damage that can occur if the motor is running in
an abnormal condition, such as out-of-synchronism.
Figure 8. Front view of CR 192 JJ.SPM
The complete Synchronous-motor Controller consists of the
Motor-starter, Switching device (typically a contactor) which
controls the main power to the motor. In addition, protective
relaying is provided (such as overload relays) and control for
starting and stopping the motor (start-stop push buttons).
Indicating devices such as line ammeters are supplied. All of
these features are common with motor controllers of all types.
6
RIBBON
RELAYS
FUSE
Figure
9.
Backbase view of CR192 JJ.SPM
In addition to full voltage starting, synchronous motors may
be started by either reduced inrush methods, such as primary
reactor, auto-transformer or part-winding control.
The following elements are unique to synchronous
controllers.
3.2.1 The CR192 micro-starting and
protection module
This electronic, microprocessor-based module provides the
computation and monitoring functions necessary to synchronize
and protect the synchronous motor from stall, prolonged
acceleration, or pull-out conditions. This device is discussed in
more detail starting in Section 4.
3.2.2 Field contactor
This low-voltage contactor applies and removes dc power
to the synchronous motor field and switches the field dis-
charge resistor. This device may be either solid state or elec-
tro-mechanical.
3.2.3 Field discharge resistor
This resistor bank (sometimes shipped as a separate item)
is used to discharge the magnetic energy of the field during
shutdown and absorb induced field energy during start-up.
Advertisement
Table of Contents
