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Inside View of Power Supply
Unit.
1. Microprocessor
based controller provides :-
Complete control of H.F. Welder sequence.
Automatic power speed control which greatly reduces open seam
tube through accurate
control of weld power at start and shut down.
2. Closed loop thyristor (SCR) power control system along with
low ripple LC filter provides
step less heat control.
1. Oil or air
colled high tension plate transformer. The transformer has high
impedence so as to limit the fault current to a max of 10 x I
rated.
2. Low Ripple LC Filter
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The main power
supply unit has the following components installed:
Enclosure
Free floor standing pressurised with all around access, dust and
fume proof enclosure, internal forced cooling by air to water heat
exchanger. Cable entry from top/bottom and water inlet-outlet from
the side (near the bottom) of the enclosure.
Main Supply Breaker
Molded case circuit breaker of suitable rating is provided as
standard.
1. Alphanumeric Intelligent Display for fault diagnostic information
and on line welder parameters.
H. T. Contractor
Triple pole power contactor of suitable rating for disconnecting the
mains supply to the equipment.
Thyristor Phase Control Unit (Automatic
Voltage Regulator)
Composed of three sets of water cooled thyristor stacks, with each
stack containing two back to back thyristors. By controlling the
phase angle of the thyristors, the welder output can be adjusted
from zero to maximum steplessly and at the same time welder output
is stabilized to +/- 1% for an input voltage variation of +/-10%
Auto Speed-Power Controller (Optional)
A closed loop electronic regulator is provided to control main
supply voltage in accordance with the output power requirement.
Oscillator Valve filament Supply Regulator
A single phase closed loop thyristor control voltage regulator or
CVT is provided to regulate oscillator valve filament supply. The
filament supply is stabilized to +/- 1.5% for an input supply
variations of +/-10%. Filament voltage is gradually set by a built
in ramp circuit.
Control Supply Transformer
Standard 110 Volts.
High Tension (Anode) Transformer
It steps up the thyristor controlled main AC voltage into high
voltage AC to feed the high voltage rectifier. Since the transformer
is located in the power supply cubical chamber, it is designed to
withstand high frequency environment.
Cooling:
Water cooled by internal water-oil heat exchanger connected to
distilled water circuit.
With the result little amount of heat is transmitted from the
transformer tank to other components. Dry type transformer is
provided as standard for North America
Impregnated windings:
Standard primary voltage - 380 Volts, 3 Phase, 50 Hz.
High Voltage Ripple Filter
Programmable Logic Controller
It is a compact and powerful PLC with real time clock and it can be
easily programmed with the help of a PC.
Metering Plate
Metering plate is mounted on the door of the power supply cubical
and is provided with the following meters, selector switches:-
(a) H.T. Voltmeter
(b) Anode current ammeter
(c) Filament voltmeter
(d) Grid current ammeter
(e) SCR output voltmeter with selector switch
(f) Line current ammeter with selector switch
(g) Emergency stop push button
Digital Display
Alphanumeric LCD back lit display provided with following function
keys:-
(a) Distilled water pump ON/OFF push buttons
(b) Weld heat ON/OFF push button
(c) Local remote selector switch
(d) Test-run selector switch
(e) Reset push button
In addition the LCD screen displays extensive fault information
Local Cooling Connections
Copper/S.S. and carbon free rubber hose pipes to avoid corrosion of
the pipe lines and contamination of distilled
water. All heat generating parts are water cooled viz. thyristor,
transformer, cooling coils etc. to the inlet and outlet connections.
Standard Protections
(a) Magnetic short circuit (Provided in the main supply MCCB)
(b) Instantaneous electronic over current trip
(c) Instantaneous DC magnetic over load relay
(d) Ambient temperature thermostat
(e) Magnetic float type water flow switch
(f) Thyristor over temperature thermostat
(g) Metal oxide varistors in the incoming lines to protect
thyristors from high voltage transient in the main supply
(h) "Spark Gap" to protect oscillator valve and other components
(I) earth droppers
(j) electromechanical door inter lock in high voltage compartment
(k) Input water over temperature thermostat
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