Introduction to Voltage Stabilizers
ELECTRICAL ENERGY HAS BECOME A BASIC NECESSITY FOR OUR
PRESENT LIVING CONDITIONS. ELECTRICAL AND ELECTRONIC EQUIPMENTS FROM ORDINARY
BULBS TO PHOTO LIGHTING ANCILLARIES FROM MINI-CALCULATORS TO SOPHISTICATED
COMPUTER STATIONS, FROM TINY TOY MOTORS TO HUGE MACHINERY MOTORS CONSUME
ELECTRICAL ENERGY. AT ANY GIVEN INSTANT A GROUP OF SUCH UNITS ARE BEING
SWITCHED ON OR SWITCHED OFF AT VARIOUS LOCATIONS THROUGHOUT POWER DISTRIBUTION
LINES. DUE TO SUCH ADDITION OR SUBTRACTION OF LOADS THE SUPPLY TERMINAL VOLTAGE
FLUCTUATES. THE VOLTAGE FLUCTUATION CAN BE CONTROLLED MANUALLY OR AUTOMATICALLY
BY VARIOUS METHODS. THE SAFEST, SUREST AND THE MOST ACCURATE OF THEM ALL IS
SERVO CONTROLLED METHOD WHICH IS WIDELY ACCEPTED.
IEEC
SERVO
CONTROLLED VOLTAGE STABILIZERS ARE DEVELOPED AFTER IMMENSE STUDY OF THE
FLUCTUATION PROBLEMS AND RESEARCH IN THIS FIELD.
IEEC
SERVO
STABILIZER IS ASSURED QUALITY CONTROL AT EVERY STAGE OF MANUFACTURE.
METHOD OF OPERATION
SERVO CONTROLLED VOLTAGE STABILIZERS MAINTAIN ACCURATE OUTPUT
BY FEEDBACK CONTROLLING BY SERVO MOTOR. THE INPUT LINE IS CONNECTED IN SERIES
WITH THE SECONDARY WINDING OF A BUCK BOOST TRANSFORMER. THE SECONDARY WILL GET
ADDITIVE OR SUBTRACTIVE VOLTAGE INDUCED FROM ITS PRIMARY. WHEN THE INPUT IS
LOW, THE SECONDARY WILL HAVE ADDITIVE VOLTAGE TO GIVE BOOSTED OUTPUT AND VICE
VERSA. THE PRIMARY OF THIS BUCK-BOOST TRANSFORMER IS CONNECTED TO THE FIXED TAP
AND VARIABLE POINT OF THE VARIAC (AUTOSTAT), WHICH IS CONNECTED ACROSS THE
INPUT SUPPLY. THE POSITION OF THE VARIABLE POINT WITH RESPECT TO THE FIXED TAP
POINT DETERMINES THE AMOUNT OF PRIMARY VOLTAGE AND HENCE THE SECONDARY VOLTAGE
OF THE TRANSFORMER WHICH BECOMES ADDITIVE OR SUBTRACTIVE. THUS THE INPUT IS
BOOSTED OR BUCKED BY THE SERIES CONNECTED SECONDARY WINDING CORRESPONDING TO THE
POSITION OF THE VARIABLE POINT OF AUTOSTAT THE VARIABLE POINT IS DRIVEN BY A
SERVO MOTOR IN THE FORWARD OR REVERSE DIRECTIONS. THE FORWARD OR REVERSE SIGNAL
IS GIVEN THROUGH A CONTROLLER CIRCUIT, WHICH IS ENERGISED BY AN OUTPUT SENSING
TRANSFORMER. THE CONTROLLER CIRCUIT WILL BE GIVING FORWARD OR REVERSE SIGNALS
TO THE MOTOR TILL THE OUTPUT IS CORRECTED TO THE REQUIRED VALUE, AS SENSED BY
THE SENSING TRANSFORMER. IF THE VARIATION IN THE INPUT VOLTAGE GOES BEYOND THE
SPECIFIED RANGE, THE BRUSH-ARM OF THE AUTOSTAT WILL BE DRIVEN TO EITHER OF THE
ENDS, THUS UNABLE TO CORRECT THE OUTPUT FURTHER. THIS HOWEVER IS LIKELY TO
CAUSE DAMAGE TO AUTOSTAT, MOTOR, ETC. TO AVOID THE SAME, LIMIT SWITCHES ARE
PROVIDED AT BOTH THE ENDS OF THE AUTOSTAT WINDING. SO THAT THE BRUSH ARM ON
REACHING THE END WILL AUTOMATICALLY CUT OFF THE SUPPLY TO THE MOTOR AND PREVENT
FURTHER MOVEMENT. IF THE VARIATION IN THE INPUT VOLTAGE REVIVES TO WITHIN THE
SPECIFIED RANGE, THE SUPPLY TO THE MOTOR COMES INTO FUNCTION AUTOMATICALLY TO
SET THE OUTPUT VOLTAGE TO ITS SPECIFIED LEVEL. ALSO WHEN THE LIMIT SWITCH CUTS
OFF THE SUPPLY TO THE MOTOR IT MAKES SUPPLY TO THE INDICATED LED TO ANNUNCIATE
THE OVER OR UNDER VOLTAGE CONDITION.
COMPONENT DESCRIPTION
BUCK
– BOOST TRANSFORMER
THE
BUCK-BOOST SERIES TRANSFORMER USED IN THE STABILIZER ARE DOUBLE WOUND AND WOUND
WITH BEST QUALITY ELECTROLYTIC COPPER CONDUCTORS AND CLASS ‘A’ INSULATED, VERY
SMALL RATING ARE OF SHELL TYPE CONSTRUCTION WHERE AS HIGHER RATING ARE OF CORE
TYPE. THE CORE MATERIAL USED ARE OF HIGH GRADE COLD ROLLED GRAIN ORIENTED
(CRGO) SILICON STEEL.
AUTO
TRANSFORMER
AUTO
TRANSFORMER USED IN THESE STABILIZERS ENSURE THE CORRECT RATED CAPACITY AND
BEST RELIABLE QUALITY FOR SATISFACTORY PERFORMANCE, THESE ARE AUTO-WOUND AND
WOUND WITH BEST QUALITY ELECTROLYTIC COPPER CONDUCTORS. CORE MATERIAL USED ARE
OF HIGH GRADE C.R.G.O SILICON STEEL.
SERVO
MOTOR
THIS IS A
LOW SPEED (60 RPM.) HIGH TORQUE BI-DIRECTIONAL SYNCHRONOUS MOTOR HAVING
INSTANT START AND STOP CHARACTERISTICS. THIS IS COUPLED TO THE AUTOSTAT THOUGHT
REDUCTION GEARS.
CONTROLLER
CIRCUIT
THESE ARE PLUG-IN TYPE AND HENCE ENABLES EASY
REPLACEMENT WHEN REQUIRED. THESE PCB’S ARE GLASS EPOXY TYPE, WITH CMRT MASKING,
WITH LEGEND MARKING AND WITH DULY PLATED FINGERS. THE COMPONENTS USED ARE
INTEGRATED CIRCUITS, TRIACS ETC, AND HENCE FULLY SOLID STATE.
TERMINATIONS
THE SMALLER
CAPACITY SINGLE PHASE UNITS HAVE TERMINATION THROUGH CORD WIRE AND 3 PIN
SOCKETS OR THROUGH TERMINAL STRIPS. HIGHER CAPACITY AIR COOLED TYPES ARE
TERMINATED THROUGH PLATED BRASS STUDS AND OIL COOLED TYPES ARE TERMINATED ON
SUITABLE BUS- BARS.
FRONT PANEL INDICATIONS AND CONTROLS
| 1. |
MAINS
'ON' L.E.D. |
|
|
|
| 2. |
INPUT BEYOND LIMIT L.E.D. AS VISUAL ALARMS FOR BEYOND LIMIT CONDITIONS. |
|
|
|
| 3. |
VOLTMETER |
|
|
|
| 4. |
VOLTMETER SELECTOR SWITCH. THIS SWITCH FACILITES TO INDICATE
EITHER
INPUT OR OUTPUT VOLTAGE. THREE PHASE S.S.O. TYPE UNITS ARE PROVIDED WITH PHASE
TO PHASE SELECTOR SWITCH ALSO. |
|
|
|
| 5. |
AUTO/MANUAL SELECTOR SWITCH. THIS SWITCH SELECTS THE UNIT TO FUNCTION
EITHER IN AUTO MODE OR IN MANUAL MODE. |
|
|
|
| 6. |
RAISE/LOWER SWITCH. DURING MANUAL MODE OF OPERATION THE OUTPUT CAN BE
INCREASED OR DECREASED WITH THIS SWITCH TO AVAIL SPECIFIED OUTPUT VOLTAGE. |
|
|
|
| 7. |
VOLT LEVEL SET POTENTIOMETER. THE OUTPUT SETTING LEVEL CAN BE ADJUSTED
BY THIS POTENTIOMETER WITHIN ± 10 VOLTS. THE RATED INPUT CONVERAGE
SHALL CORRESPONDINGLY SHIFT WHEN THE OUTPUT SETTING IS DISTURBED FROM THE
SPECIFIED OUTPUT. |
·
MAXIMUM EFFICIENCY
·
LOW INTERNAL IMPEDANCE
·
ZERO WAVEFORM DISTORTION
·
ZERO PHASE SHIFT
·
NO EFFECT ON SYSTEM POWER FACTOR
·
NO EFFECT ON FREQUENCY VARIATION
·
FAST CORRECTION RATE