Download Generation of high voltage

Generation of high
voltage
Types of test voltages:
•AC
•DC
•aperiodic voltage impulse
•high frequency damped voltage impulse
Generation of HVAC
Generation of HVAC
Fisher transformer:
Generation of HVAC
insulation
high voltage
winding
low voltage
winding
Generation of HVAC
Divided secondary winding:
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:
high voltage
low voltage
insulating
legs
Generation of HVAC
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
3x750 kV Dessauer-circuit:
Generation of HVDC
Generation of HVDC
DC parameters:
U peak max − U peak min
Ripple:
h=
Linear mean value:
U = U peak min + h
Polarity:
2
Positive or negative to the ground.
High voltage rectifiers
Semiconductor diode
a) conducting state; b) closed state
High voltage rectifiers
High voltage diode chain with potential controlling
resistors and capacitors
High voltage rectifiers
Current of the diode during charging:
U
I= e
R
∞
Wi = ∫ i dt
2
0
−
t
RC
WC
1
2
Wi =
CU =
2R
R
High voltage rectifiers
High voltage vacuum diode
High voltage rectifiers
Vacuum diode
a) conducting state; b) closed state
a)
b)
High voltage rectifiers
a) conducting state;
a)
b) closed state
b)
High voltage rectifiers
High voltage rectifiers
Graetz-circuit:
Voltage increasing circuits
Greinacher-circuit:
Voltage increasing circuits
Greinacher-circuit:
Voltage increasing circuits
Villard-circuit:
U = = U C + U CS sin ωt = U CS (1 + sin ωt )
Voltage increasing circuits
Villard-circuit:
Voltage increasing circuits
DC cascade circuit
Electrostatic generators
Van de Graaff-generator:
a) external excited;
b) self excited
a)
b)
Electrostatic generators
Electrostatic drum generator:
Elektrosztatikus generátorok
Principle of the condenser generator:
Q = C1U g = C2U k
C1
Uk =
Ug
C2
A
C1 = ε
d1
d1
A
> C2 = ε
d2
> d2
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%
Parameters of the voltage impulses
Switching impulse:
Th
Parameters:
- Ucs: peak value,
tolerance ± 3%
- Tcs: front time,
tolerance ± 20%
- Th : half value time, tolerance ± 60%
Parameters of the voltage impulses
T f [ µ s]
T h [ µ s]
Lightning
1,2
50
Switching
250
2500
Mathematical form of the voltage impulse
U (t ) = U 0 (e − at − e − bt )
Impulse generators
Circuit diagram
1
1
U ki (t ) = U ⋅
⋅
⋅ (e − at − e −bt )
Rcs ⋅ Ct b − a
C L + CT
b=
C L ⋅ C T ⋅ RCS
Uki:
U:
1
a=
(C L + C T ) ⋅ R K
can be set by the sparkgap
determines the repetition frequency of impulses
Impulse generators
Multistage circuit:
Structure of impulse generators
Principle of the trigger spark gap:
Syncronizer
Impulse
generator
Trigger imp.
Structure of impulse generators
High voltage, low inductive resistor: