Introduction; Overview; General Description; Functional Overview - GE SPM Series Instruction Manual

1 INTRODUCTION

1 INTRODUCTION 1.1 OVERVIEW
The SPM controls starting, synchronizing, and protection of collector-ring and brushless type synchronous
motors.
The SPM control functions for starting synchronous motors include accurate sensing of motor speed and rotor
angle, allowing the unit to apply excitation at optimum speed and angle. This permits closer matching of the
motor to the load. Optimum application of excitation also reduces power system disturbance, which occurs
when the motor goes through a complete slip cycle with the field energized. In addition, the SPM can take
advantage of the extended stall time of a reduced voltage start. It also responds with the proper application of
excitation in the event that the motor synchronizes on reluctance torque.
The SPM provides the functions necessary to protect the motor during startup and in the event of asynchro-
nous operation. During startup and restarting, the SPM prevents overheating of the cage winding. To protect
against asynchronous operation, the motor power factor is monitored. Two modes of pull-out protection can trip
the motor if resynchronization does not occur after a programmed time delay. Motor run time and the number
and type of trips are recorded.
The SPM has an optional power factor regulator containing five adjustable setpoints that can be changed while
the motor is running for convenient regulator tune-up.
A backlit LCD display and keys allow user configurable setting ranges to meet many applications. The unit
comes in a compact S1 drawout case.
The SPM can be applied as part of a complete synchronous motor controller. This consists of four parts. A
main device switches the motor on and off the power system. Multifunction digital relays (such as the GE
Power Management 469 Motor Management Relay) provide stator protection. DC field protection and control
are provided by the SPM. The field contactor and field discharge resistor completes the control assembly.
The DC portion of the synchronous motor (rotor assembly) is protected and controlled using a drawout micro-
processor based multifunction relay. The relay is adaptable to either collector-ring or brushless type synchro-
nous motors. Protection features include all of the following:
• Cage winding and stall protection during start
• Lockout feature to protect a hot rotor after an incomplete start
• Incomplete sequence trip due to failed acceleration
• Automatic acceleration time adjustment for reduced voltage starting
• Power factor (pull-out) trip with auto resynchronizing feature
• Loss of DC field current trip
• Loss of DC field voltage trip
• Field winding overtemperature trip
After a successful start, the relay automatically applies the DC field to the rotor at a prescribed slip and slip
angle to minimize mechanical stresses to the shaft as well as minimizes possible electrical transients to the
power system. This is achieved by a dedicated output to close the DC field contactor. The relay is also capable
of reluctance torque synchronizing (collector-ring machines only).
A dedicated output is provided in the relay to enable the loading of the motor following the DC field application
and unloading of the motor following a trip and/or loss of synchronization (pole slipping).
Control of an SCR type excitation system by means of an analog output to maintain power factor (PF regula-
tion) is available as an option.
GE Power Management SPM Synchronous Motor Protection & Control

1.1 OVERVIEW

1.1.1 GENERAL DESCRIPTION

1.1.2 FUNCTIONAL OVERVIEW

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