Hubbell 4922c manual 4922C, For Hoists Without Mechanical Or Eddy Current Brakes

Hubbell Industrial Controls, Inc.	4922C
S2MC Compact Primary Thyristor Controller

For Hoists Without Mechanical Or Eddy Current Brakes

Catalog 4922C • May 1993

General

The Type 4922C S2MC primary thyristor static reversing controller system provides speed-regulated con- trol of hoist with wound rotor motors and without load brakes. The Type 4922C system includes the controller and for separate mounting the Type 5410 tachome- ter/overspeed switch assembly and Type 3000 secondary resistor.

The operator control is a Type 4216 stepless mill master switch. Type 4211 stepless mini master switch or Type 2015/6/7 stepless pendant pushbutton station. Full range of motor speed from minimum to maximum is ad- justed by the stepless operator. Hoisting speed, with or without load, is closely controlled by varying the motor pri- mary voltage with thyristors. No-load lowering speed is handled in the same manner. Lowering speed of an over- hauling load at subsynchronous speeds is controlled via counter-torque control.

4922C controllers are available from 10 to 250 HP at 460/3/60 VAC.

Operation

Hoisting: When the hoisting direction is selected, the M contactor closes and hoisting torque is produced by the motor when selected primary thyristor modules begin conduction. The amount of thyristor modules begin con- duction. The amount of thyristor conduction and hence, motor hoisting torque, is determined by the master switch speed reference signal and the tachometer speed feedback signal. In this manner, stepless adjustable speed control is obtained for hoisting.

Lowering: When the lowering direction is se- lected, the M contactor closes and the selected primary thyristor modules begin conduction.

If the hook is empty or lightly loaded, the controller will maintain the motor in a stepless speed regulated "driv- ing lower" condition.

If the load overhauls the motor, the controller will turn off (2) of the thyristor modules and turn on the other (2) thyristor modules. This transition converts the motor op- eration from a driving lower condition to a counter-torque condition with hoisting torque controlling the descending overhauling load in a controlled stepless manner.

As full speed is reached, the controller reverts back to a drive down mode and the motor is placed into regeneration. When leaving the regenerative lowering mode, the controller reverts back to counter-torque lower- ing.

Features

The Type 4922C standard controller includes the following major components/features:

S2MC Compact Variable Speed Control As- sembly consisting of (1) regulator PC board and (2) firing circuit board. All adjustments, potentiometers, and test points for setup and fine-tuning plus status lights are front- panel-mounted and clearly identified. Simple test setup readings require use only of a VOM meter.

Five (5) conservatively rated Type 5410 Full Wave Thyristor Power Modules with MOV transient volt- age protection and snubbing circuits to limit rate of voltage rise. Thyristor modules for 40HP/460 volt and under are mounted with the S2MC Compact Speed Regulator Assem- bly. Over 40HP the thyristor modules are separate mount within the controller enclosure.

S2MC Tachometer Continuity Module monitors the tachometer feedback signal and shuts down the con- troller in the event of an open tachometer signal.

In addition to the S2MC modules the Type 4922C controller features a three-pole main knife switch. NEMA rated mainline contactor, (3) Inverse time trip overload re- lays, fused control knife switch, 120 volt control trans- former, low voltage relay and a shunt brake relay.

Optional Features

Full Speed Contactor: The 4945C hoist system requires a secondary slip resistor to provide optimum torque at reduced speeds, but results in a 20% slip at full load/full speed. The full speed contactor shorts out this resistor at high speed and allows the motor to obtain its maximum rated base speed.

Extended Slow Speed Operation: This option allows the hoist to operate at reduced speeds for an ex- tended period of time. Recommended for die handling cranes and turbine handling cranes.

Five Step Reference Board: This option allows the controller to operate from a standard 5 step sequential master switch or pendant. Each step can be independently set for a fixed speed.

Multi-panel Construction: This option provides two or more controllers to be mounted in a common enclo- sure and interwired with a mainline contactor panel.

Other standard modifications and options are available. Consult factory for assistance.

Page 1 of 2