High Voltage and High Frequency Power Supply for Insulators Testing
Transmission line system having insulators where insulation plays an important role in supporting towers. For this reason, it is very much important that their insulating properties must be tested first. So, one of such properties is flashover testing to verify material defection such as
2025-06-28 16:32:53 - Adil Khan
High Voltage and High Frequency Power Supply for Insulators Testing
Project Area of Specialization Electrical/Electronic EngineeringProject SummaryTransmission line system having insulators where insulation plays an important
role in supporting towers. For this reason, it is very much important that their
insulating properties must be tested first. So, one of such properties is flashover testing
to verify material defection such as tiny holes etc. In today’s world we see that the
industrial technical trend for high-voltage power supply is to increase the power density
and reduces its weight and volume. For the reduction of volume and lead to higher power-
density design high frequency is used. The other reason for using high frequency is that
it can reduce the HV capacitance of voltage multiplier in a high voltage supply.
This Final Year Project (High Voltage and High Frequency Supply for Insulators Test-
ing) presents the design and construction of a high-voltage and high-frequency power
supply for pin type insulators testing. Transmission line system having insulators where
insulation plays an important role in supporting towers. For this reason, it is very much
important that their insulating properties must be tested first. Frequency for his power
supply is in range of 90-100 kHz and voltage is up to 20 kV. Basic purpose of such kind of
supply is to observe the effect of high frequency with high voltage on pin type insulators.
Due to its characteristics of high-frequency source, surface of defective insulator can be
easily be searched out. A proposed solution for the design of this supply will be given
such that firstly AC-DC conversion is done by an adopter up to 24 V DC (which is an AC
to DC step down conversion by transformer and rectifier bridge). We are using SPWM
(Square pulse width modulation) technique to generate an AC signal with high frequency
from DC signal. For this purpose, we are using an IC SG-3225 or KA-3525 to generate
SPWM of 100 kHz frequency. PWM’s frequency depends on timing of resistance and
capacitance. The resistance between pin number 5 and pin number 7 (RD) of SG-3525
determines the dead time and also merely affects the frequency. Driver Circuit (build
by some connections in PCB) is used to drive the MOSFETs. We Used a high voltage
transformer to get voltage level up to 20 kV. Transformer’s winding parameters of both
windings is determined by searching from different books like Transformer and Inductor
Design Handbook (Fourth Edition) by Colonel Wm. T. McLyman. Considering high
frequency effect we also determined the size of specific core from this book. Epoxy resin
is used to support the insulation level at high voltage for the transformer. Total setup is
used to test pin type insulators.
Our experimentation approach is firstly done on Proteus:
made its PCB layout and the we studied a research paper for this purpose and
implement the model. Firstly, we did the PWM modulation for 33 kHz.After we tested our circuit on bread board for 33 kHz, getting the successful results we
test it for 100 kHz.
After that we check the behaviour of our while MOSFETs IRF450 in service with the center tapped primary winding transformer (alternative) paths for both MOSFETs) is attached to them. The sinusoidal wave form in the Figure 7.3 is done by using a transformer
which gives the output in the ratio 24:220 V AC. The
inverter PCB and all the necessary components with capacitor, resistors and MOSFETs,
The final setup is the combination of this high frequency inverter is with the HVF (high
voltage and frequency) transformer the whole detail of 24 V to 20 kV. Frequency is also checked with the frequency meter that also confirms that
100 kHz is there, aHF frequency meter that is used from this purpose.But for that combination high voltage is difficult to measure. Simple CRO cannot work
under that condition because they work at voltage up to 400V, but in our case it is 20
kV.The three golden colour wires for
the three connectors at the end of HF inverter and the blue and black coloured wire is
for the output of 20 kV. Epoxy resin of green colour as shown in figure is for insulated
purpose, it is necessary as in air HV is difficult to measure. Specific HV probe is used to
measure that voltage in addition that the output power is low in our case.
The use of High Voltage supply is to increase the power density and to lessen the
overall size and weight of supply. This is mainly driven by portable and mobile
applications. High frequency inverters also reduce the size of passive components as well.
For surety to check the performance of insulating material, it should be tested several
times.
Mainly, there are three types of tests which are performed on insulators like: Flashovertests of insulator, Performance test, Routine tests. The overhead outdoor insulator hav-
ing the ability of bear high voltage surges that are caused by lightning etc. So
the insulation must be tested against high voltage surges. So, a high-impulse voltage
and high-frequency test must apply on insulators. Power [10] [11] supplies operating at
high-frequency and high-voltages having many applications in airborne equipment like
radar transmitter systems, power systems for conditioning and for spacecraft’s etc. This
is due to the reason that the frequency is inversely proportional to weight of equipment
so as frequency becomes high the size/weight of instrument/equipment reduces as like in
air born applications. It is necessary to develop the use of capacitors which are working
at higher frequencies for application like space-based. This gives an interesting concept
about HV stresses in the mind of author
Parallel tank capacitor gives the same concept of oscillatory circuits for HV and HF. The frequency could be varied up to 90 kHz or more while the voltages could be
varied up to 19 kV (p-p). 10-12.5 pm is most;y is the thickness of an insulating material.
Amount of electricity, its cost and its quality are the most important figures in mod-
ern world. One reason for this is failure of expensive equipments in various areas is the
poor quality of electricity. It is seen that many electrical equipments like transform-
ers, line conductors, rotating machines, etc. gives unwanted electrical signals in the radio
and high-frequency ranges of like television band, microwave bands, etc. Signal in-
creases its value due to corona discharge. Insulating produces causes noise when binding
of HV conductor with metal pins take place..
RIV (Radio Interference Voltage) testing apparatus for Pin-Type Insulators is the final deliverable hardware which we need because of excessive use of pin-type insulators in a power systems
and their use in most of the transmission grids. High frequency i.e 100 kHz, reduces
the size, volume and overall cost of the apparatus. We achieved high-voltage and high-
frequency at the same time. Both high-voltage impulse and high-frequency tests applied
on insulator with the help of this apparatus. Several tests are implemented and various
results concerning different conditions has been performed. This apparatus is not common
now a days but will be common in future because future is of Smart grids. Our project
leads to an Entrepreneur that “The high Voltage and high frequency Power Supplies”
used for plasma operations and researches.
| Item Name | Type | No. of Units | Per Unit Cost (in Rs) | Total (in Rs) |
|---|---|---|---|---|
| Total in (Rs) | 50320 | |||
| PCB design | Equipment | 1 | 3250 | 3250 |
| Sinks | Equipment | 10 | 60 | 600 |
| Diodes | Equipment | 20 | 25 | 500 |
| Resistors | Equipment | 20 | 10 | 200 |
| Small HF transformer for testing | Equipment | 1 | 5200 | 5200 |
| 24V DC adopter | Equipment | 2 | 750 | 1500 |
| MOSFETs 1RF450 | Equipment | 8 | 280 | 2240 |
| Necessary HF transformer design | Equipment | 1 | 22500 | 22500 |
| Epoxy | Equipment | 1 | 700 | 700 |
| Encapsulation | Equipment | 1 | 750 | 750 |
| SG 3525 IC | Equipment | 10 | 138 | 1380 |
| Wires and jumpers | Equipment | 80 | 5 | 400 |
| Final touching | Miscellaneous | 1 | 2000 | 2000 |
| Casing | Equipment | 1 | 2800 | 2800 |
| Travelling | Miscellaneous | 1 | 4000 | 4000 |
| Phone calls | Miscellaneous | 1 | 500 | 500 |
| Printing | Miscellaneous | 1 | 1500 | 1500 |
| Stationary | Miscellaneous | 1 | 300 | 300 |