The invention relates to a high voltage high energy variable surge generator device which generates a high voltage impulse of reuired voltage, energy and time. The high voltage surge generator is used for testing of thyristor switches and other high voltage equipments. In many other applications, a very high energy is required for testing purpose. BACKGROUND OF THE INVENTION
In the present known methods, energy is stored in a high voltage capacitors and a surge is generated using high voltage expensive thyristors. This requires all components like insulator, reactor, diode, transformer etc. to be rated for high voltage rating.
There are disadvantages associated with the present system of surge generator devices. One of the main disadvantages is that the euipment becomes very expensive during initial and as well as repairing stages.
Another disadvantage associated with the present system of surge generator device is that it is bulky and difficult to operate and maintain.
Yet another disadvantage associated with the present system of surge generator is that it is not very safe in its operation. SUMMARY OF THE INVENTION
Therefore, the main object of the present invention of a variable surge generator device is that it uses cheaper and safer low voltage components.
Another object of the present invention of a variable surge generator device is that it is smaller in size, and is user friendly.
Yet another object of the present invention of a variable surge generator device is that it is more reliable and give a variable output.
Still another object of the present invention of a variable surge generator device is that it produces high energy capable to drive capacitive load and have an output of 7KV peak pulse across 1/^ F capacitor.
Further object of the present invention of a variable surge generator device is that it has short circuit proof and open circuit proof output and is safe to operate.
According to the present invention there is provided a high voltage high energy variable surge generator device comprising a charging circuit providing variable charge to a capacitor of the circuit which provides a low voltage pulse to high voltage transformer for a high voltage output with user controls and interlocks provided on the front panel of said device.
The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to non - limiting exemplary embodiments of the invention represented in the accompanying drawings.
Figure 1- electrical circuit diagram of the device according to the invention
Figure 2- shows the voltage across the output of generator and resistor.
Figure 3 - voltage across resistor under short circuit condition of generator output. Description of the Invention;
The main circuits of the device of this invention broadly comprises as :
a) charging circuit (1)
b) L-C circuit (2)
c) High Voltage transformer (3) '
d) User controls and interlocks (4)
The electrical circuit diagram is as shown in Fig. 1 and / the charging circuit (1) comprises an auto transformer (T1 ), a resistor (R, ) and a full wave rectifier (D, , D„, D„, D the L-C circuit (2) comprises a low voltage capacitor (C a voltmeter (V) connected across and an inductance (1/ voltage transformer (3) as represented by an i § o^iting" transformer (T2) and uses controls and interlocks as ajrious switches, relays with contacts connected to input.
The auto - transformer has to be at minimum voltage position. The auto-transformer's minimum position limit switch contact closes. Now the operation of switches Si and S2 turns ON relay K2. When the relay K2 switches ON, its normally open contact (K21) closes and keeps the charging circuit ON. The charging circuit consists of an auto-transformer (Tl), a full wave rectifier (D1-D4) and a current limiting resistor Rl. A low voltage capacitor C is charged by this circuit. A DC voltmeter (V) is connected across the capacitor to measure the voltage. The capacitor is charged to desired voltage by varying the auto transformer. Now a surge can be applied using switchS3. When switch S3 is operated the relay Kl becomes ON. The relay Kl connected to switch S3 switches ON resonance circuit and also switches off input to auto-transformer (Tl) automatically. This relay contact (K13) connects capacitor C to inductance L. The combination of capacitance (C), inductance of reactor (L), reactance of transformer (T2) and load impedance forms a resonance circuit and a pulse is generated at low voltage.
The isolating transformer T2 keeps the output at zero voltage under capacitor (C) changed condition. The resonance circuit generates upto 7KV across I ytl F load. The peak voltage of surge can be varied to any value using auto-transformer (Tl). The high voltage output of the surge* generator is open circuit and as well as short circuit proof. A lock in switch provided in Auto transformer (Tl) allows switching of equipment at minimum voltage only.
This low voltage pulse is converted to high voltage using specially designed transformer T2. The transformer is of high efficiency and has a low impedance. Relay Kl by contact (K12) also disconnects input to the charging circuits for protection purpose. Contact Kll is used to latch Kl relay. Kll, K12 and K 13 are the contacts of relay Kl. Similarly K21 is the contact of relay K2.
The equipment requires 230V AC supply to be connected across input terminals. The load is to be connected across high voltage output terminals. The design of the generator is such that the voltage at the output remains zero under capacitor charge condition. This is due to insulation of transformer T<22. The user controls and indications are provided on the front panel. The input and output connections are also provided on the front panel for easy access. The high voltage output terminals are mounted on bakelite plate to provide necessary insulation./ The limit switch protection provided, allows restart of high voltage circuit at minimum position of auto transformer only. Wheels are provided at the bottom plate for easy mobility. The surge generator will be able to give upto 7kV pulse across ljMF load Resistance R3 is provided to dissipate energy during short circuit condition. Resistance R2 is provided to limit output voltage during output open condition.
The Surge Generator was used to test the high voltage protective feature of a thyristor equipment, results of which are shown in fig. 2. In fig. 2, plot C2 shows the voltage across
the output of generator ( using 1000:1 probe).Output was adjusted
to 6.4kV to meet load requirement. The plot CI of Fig. 2 shows
the voltages across resistor R3 (using 10:1 probe). The voltage
across R3 is shown in Fig. 3 (using 10:1 probe) under short
circuit condition of generator output.
The invention described here in above is in relation to
non-limiting embodiments and as defined by the accompanying
claims.

We Claim
1. A high voltage high energy variable surge generator device comprising a charging circuit (1) having an auto transformer (Tl) providing variable charge to a low-voltage capacitor (C) attaining a desired voltage, a switch (S3) connected to a relay (Kl) to generate a surge thereby connecting the capacitor (C ) to an inductance ( L ) to form a resonance circuit which generates a low-voltage pulse; a plurality of users control and interlocks (4) to monitor and control the device, characterized in that an isolating transformer (T2) disposed at a distal end for converting the low-voltage pulses to high-voltage pulses.
2. A device as claimed in claim 1 wherein said charging circuit (1) comprises an auto transformer (Tl) connected to a current limiting resistor (R1) and a plurality of full wave rectifier (D1, 02, 03, 04) for charging the bw voltage capacitor (C ), said bw voltage capacitor (C ) being connected to the inductance (L) through a relay contact (K13).
3. A device as claimed in claim 1 wherein said isolating transformer (T2) is a high voltage transformer having high efficiency and low impedance.
4. A device as claimed in claim 1 wherein said User controls and interlocks (4) comprises switches (S1, S2) relays (Ki), relay contacts (K11 K12, K13, K21) and contact (Tn) for the auto transformer (Ti), the circuitory being connected to a 230V input.
5. A device as claimed in claim 4 wherein the switches (S1, S2) and the relay (K2) are assigned to the auto transformer (T1).
6. A device as claimed in claims 2 and 3 wherein,said bw - voltage capacitor (C ), said inductor (L) and said auto transformer (T2) and the load

impedance in combination forming the resonance circuit to generate the low voltage.
7. A device as claimed in claim 1 wherein said resonance circuit generates up to 7KV across 1µF, said peak voltage is adjustable by said auto transformer (T1).
8. A high voltage high energy variable surge generator device as herein described and illustrated with the accompanying drawings.