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Cutler-Hammer EATON Ampgard Mark V Instructions Manual

Solid-state, brush-type, synchronous motor controllers

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Cutler-Hammer
Instructions For Ampgard
Brush-Type, Synchronous Motor Controllers
HAZARDOUS VOLTAGE.
READ AND UNDERSTAND THIS BOOKLET AND ITS
RELATED INSTRUCTION MATERIAL FOR FULL-
VOLTAGE CONTROLLERS IN THEIR ENTIRETY
BEFORE INSTALLING OR OPERATING THE
CONTROLLER. SEE TABLE 1.
INSTALLATION, ADJUSTMENT, REPAIR AND
MAINTENANCE OF THIS TYPE OF EQUIPMENT MUST
BE PERFORMED BY QUALIFIED PERSONNEL. A
QUALIFIED PERSON IS ONE WHO IS FAMILIAR WITH
THE CONSTRUCTION AND OPERATION OF THIS
EQUIPMENT AND THE HAZARDS INVOLVED.
SYNCHRONOUS MOTORS
Polyphase synchronous motors have stators similar to
squirrel-cage induction motors and most have rotors with
DC slip-ring circuits which must be energized for normal
operation. The controller described in this booklet is for a
synchronous motor with slip rings and brushes.
Synchronous motors operate at constant base speeds
corresponding to line frequency and the number of ma-
chine poles (revolutions/min = 120 x frequency/number of
poles). They are employed primarily to obtain high pullout
torques, constant operating speeds, or generation of
leading reactive VA (VAR) for system power-factor correc-
tion. They require conventional AC polyphase power
sources for their stators and suitable DC power sources
for their rotor fields.
For normal operation, synchronous motors must be
brought to near full operating speed, at which point the DC
power is connected to the rotating field through brushes
and slip rings. The motors are accelerated to their syn-
chronizing speeds by means of either built-in start wind-
ings or external auxiliary drives. Nearly all conventional
synchronous motors now manufactured have built-in rotor
starting windings. Such starting windings are also referred
to as squirrel-cage windings, pole-face windings, damper
windings, or amortisseur windings. Start windings are
actually squirrel-cage induction bars located in the faces
Effective 11/97
DANGER
®
Mark V Solid-State,
TABLE I. REFERENCE MATERIAL
Contactor
Type
Type SJA
Type SJA
Type SJD
Type SJO
Type SJO
Type SJS
of the DC rotor poles. They produce accelerating torque
only and have short-time intermittent duty ratings. As
start windings, they become inoperative at synchronous
speeds but serve to dampen any tendency of the rotor to
oscillate in angular position with relation to the stator field.
The starting of synchronous motors involves two basic
switching functions. The first is the energizing of the
stator to produce breakaway torque and acceleration to
near synchronous speed, the second is the energizing of
the DC rotor field at the optimum speed and rotor-stator
pole relationship. For motors having built-in start wind-
ings, the same equipment considerations are required as
for full-voltage or reduced-voltage starting methods used
for squirrel-cage induction motors. All factors relating to
the stator circuits are identical.
Synchronous motors have two torque characteristics,
starting torque and running or synchronous torque. The
first is determined by the squirrel-cage design and the
"slip" as the motor accelerates from zero to near synchro-
nous speed. "Slip" is expressed as a percent fraction
where the numerator is the difference between the syn-
chronous speed and the non-synchronous speed, and the
denominator is the base speed, all speeds expressed in
revolution per minute (rpm). The running torque character-
istic (at synchronous speed) is produced by the magnetic
fields created by the DC field coils in the rotor which link
with the rotating fields produced by the AC current in the
stator windings. See Figure 1.
The DC field coils are energized via two slip rings and
brushes. The DC voltage applied to the field coils can be
varied to produce the desired level of direct current which
in turn produces a magnetic field through each pole which
can be varied. Once at synchronous speed,
I.B. 48008
Ampere
Instruction
Rating
I.L. or I.B.
360A
I.B. 48002
720A
I.B. 48005
360A
I.B. 48004
360A
I.L. 16-200-33
720A
I.L. 17047
360A
I.B. 48003

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Summary of Contents for Cutler-Hammer EATON Ampgard Mark V

  • Page 1 Cutler-Hammer I.B. 48008 ® Instructions For Ampgard Mark V Solid-State, Brush-Type, Synchronous Motor Controllers TABLE I. REFERENCE MATERIAL Contactor Ampere Instruction DANGER Type Rating I.L. or I.B. Type SJA 360A I.B. 48002 Type SJA 720A I.B. 48005 HAZARDOUS VOLTAGE. Type SJD 360A I.B.
  • Page 2 I.B. 48008 Page 2 SYNCHRONOUS MOTORS (Continued) changing the field current can change the power factor at which the synchronous motor runs or the reactive current drawn from the AC line. A synchronous motor cannot start with its DC pole windings excited.
  • Page 3 I.B. 48008 Page 3 the field has not yet been energized by the DC power supply, or the converse, the motor coasting to a stop with the field deenergized. The controller protective functions include: 1. Locked-rotor protection 2. Incomplete-sequence protection 3.
  • Page 4: Controller Operation

    I.B. 48008 Page 4 Mark V Controller Functions (Cont.) RLY1 and RLY3 may pulse open and closed during certain types of faults causing the interposing relay “MX” to drop The SCR field power supply QA1, QB1, QC1, QA2, QB2, out, insuring that the “M” contactor has dropped out. SYTR and QC2 supplies voltage (125 or 250 VDC) and current to remains energized until “M”...
  • Page 5 I.B. 48008 Page 5 Fig. 4 Mark V Controller Schematic When the motor is running at rated speed and the line The minimum output voltage can be adjusted from 50% to contactor (M) opens, the gating must be inhibited to SCRs 70% of nominal voltage (125 or 250 VDC) with a potenti- QA1 to QC2.
  • Page 6 I.B. 48008 Page 6 220/240 VAC Operation OPTIONS Each of the six variations rated by field supply output To operate the synchronizing and control circuit board current and voltage (50, 100, or 200 amperes at either from a 220 or 240 VAC supply, add three jumpers to the 125 or 250 VDC) will perform with any combination of 240V terminals above T1, T2, and T3 and one terminal to user selected options as determined by jumpers inserted...
  • Page 7: External Inhibit

    I.B. 48008 Page 7 Fig. 5 Synchronous Control Board Layout SYSTEM PROTECTION EXTERNAL INHIBIT This controller includes circuits that provide a means of If the controller contains an autotransformer for reduced- shutting down in the event of a stalled motor, excessive voltage starting, DC voltage will not be applied until after start time (time-out period exceeded), or pole slippage transition to full voltage.
  • Page 8: Rotary Switch Settings

    I.B. 48008 Page 8 SYSTEM PROTECTION (Continued) circuit. These contacts are available at terminals SQ1 and SQ2 of Terminal Board 1 (TB1). See Figure 6. RLY1 (see Figure 6) becomes energized about 50 millisec- onds after power is delivered to the printed circuit board and proper operational status of the controller is estab- lished.
  • Page 9 I.B. 48008 Page 9 AUTOTRANSFORMER STARTER OPERATION The field power thyristors will be held OFF until the 115 VAC inhibit signal and the proper slip frequency have appeared. The 2.5 to 3.5 second synchronizing period also will not start until both these conditions are met. When the controller is used in conjunction with a reduced-voltage motor controller, the gating is inhibited until full voltage is applied to the motor.
  • Page 10 I.B. 48008 Page 10 Synchronous Motor Check Each Mark V synchronous motor controller has a terminal strip consisting of seven studs on standoff insulators mounted on a subpanel and labeled as shown in Figure 8. Disconnect leads from these stabs as necessary to conduct the following tests: 1.
  • Page 11 I.B. 48008 Page 11 Full Operation Static Field Test 1. Open isolating switch. Verify the field supply output without energizing the motor as follows: 2. Reconnect motor leads. 1. Install contactor and all fuses. 3. Close and latch all doors. 2.
  • Page 12 Incomplete Sequence ..........6 Time-out Option ............6 Mark V Controller ............. 3 VAR Option ............... 8 Motor Controller ............2 Voltage Options ............6 Motor Field Excitation ..........2 Cutler-Hammer 221 Heywood Road Arden, NC 28704 Effective 11/97 Printed in U.S.A./CCI...