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Generation of high
voltage
Types of test voltages:
•AC
•DC
•aperiodic voltage impulse
•high frequency damped voltage impulse
Generation of HVAC
Fisher transformer:
Generation of HVAC
low voltage
winding
high voltage
winding
insulation
Generation of HVAC
Divided secondary winding:
Generation of HVAC
Test transformers
T1: low voltage winding
N1,N2: high voltage windings
K1,K2: flux balancing windings
Iron core must be insulated from the ground!!!
Generation of HVAC
Divided secondary winding:
Generation of HVAC
Transformer with divided secondary winding in insulating
housing:
Generation of HVAC
Transformer with divided secondary winding in metal
housing:
insulating
legs
low voltage
high voltage
Structure of a test
transformer with
open iron core
Generation of HVAC
Compensation of the capacitive load with inductance:
Generation of HVAC
Stepped transformers:
Generation of HVAC
Dessauer-circuit of test transformers:
Generation of HVAC
Cascade circuit
of test transformers:
Generation of HVAC
3x750 kV Dessauer-circuit:
Generation of HVAC
Generation of HVAC
3x750 kV Dessauer-circuit:
Generation of HVDC
DC parameters:
2
minmax peakpeak UUh
−=Ripple:
Linear mean value:
Polarity: Positive or negative to the ground.
hUU peak += min
Generation of HVDC
High voltage rectifiers
Semiconductor diode
a) conducting state; b) closed state
High voltage diode chain with potential controlling
resistors and capacitors
High voltage rectifiers
Current of the diode during charging:
RC
t
eR
UI
−=
R
WCU
RW Ci == 2
2
1∫∞
=0
2dtiWi
High voltage rectifiers
High voltage vacuum diode
High voltage rectifiers
a) b)
High voltage rectifiers
Vacuum diode
a) conducting state; b) closed state
a) b)
High voltage rectifiers
a) conducting state; b) closed state
High voltage rectifiers
Graetz-circuit:
High voltage rectifiers
Greinacher-circuit:
Voltage increasing circuits
Greinacher-circuit:
Voltage increasing circuits
Voltage increasing circuits
Villard-circuit:
)sin1(sin tUtUUU CSCSC ωω +=+==
Villard-circuit:
Voltage increasing circuits
DC cascade circuit
Voltage increasing circuits
Electrostatic generators
Van de Graaff-generator:
a) external excited;
b) self excited
a) b)
Electrostatic drum generator:
Electrostatic generators
Elektrosztatikus generátorok
Principle of the condenser generator:
kg UCUCQ 21 ==
gk UC
CU
2
1=
2
2
1
1d
AC
d
AC εε =>=
21 dd >
Generation of high voltage impulses
Parameters of the voltage impulses
Lightning impulse:
Parameters: - U: peak value, tolerance ±±±± 3%
- Tf: front time, tolerance ±±±± 30%
- Th : half value time, tolerance ±±±± 20%
Switching impulse:
Parameters of the voltage impulses
Parameters: - Ucs: peak value, tolerance ±±±± 3%
- Tcs: front time, tolerance ±±±± 20%
- Th : half value time, tolerance ±±±± 60%
Th
T f [µµµµs] T h [µµµµs]
Lightning 1,2 50
Switching 250 2500
Parameters of the voltage impulses
Mathematical form of the voltage impulse
)()( 0
btat eeUtU −− −=
Impulse generators
Circuit diagram
)(11
)( btat
tcs
ki eeabCR
UtU −− −⋅−
⋅⋅
⋅=
CSTL
TL
RCC
CCb
⋅⋅
+=
KTL RCCa
⋅+=
)(
1
Uki: can be set by the sparkgap
U: determines the repetition frequency of impulses
Multistage circuit:
Impulse generators
Structure of impulse generators
Principle of the trigger spark gap:
Impulse
generator
Trigger imp.
Syncronizer
High voltage, low inductive resistor:
Structure of impulse generators