Description

“NTPL” MAKE 300KV/5KJ LIGHTNING IMPULSE VOLTAGE GENERATOR TYPE: IMGNT-300K5KJ

It is important to perform impulse voltage test on electrical equipment chosen as sample to check the insulation coordination of the same. It is found that either the lightning over voltage or switching phenomena from where the impulse voltage is generated in the electric power transmission and distribution system can be simulated by generation of impulse voltage of particular shape in the test laboratory. “NTPL” make Impulse generator will be made according to  relevant  I.S.  specification  to meet the exact requirement as under. The Joules output is here suitable for testing…………

• Transformers
• Short Length of Cable
• Instrument Transformers
• Insulators and Bushings
• Isolators
• Circuit Breakers etc. for which voltage and energy requirement is within the scope of this test system.

Technical Particulars:

Input voltage                                :             230V, 1 phase, 50Hz. AC.

Maximum Impulse Voltage      :              300KV Peak.

Power/ Stored energy                :             5KJ at max. voltage.

No. of stages                                :             3

Nature of Impulse Wave           :             1.2/50 mSec.

Accuracy  Rise Time/Fail time:              +30%/+20%

Polarity                                           :             Positive & Negative-selectable.

 

The above multistage Impulse Generator will be consisting of the followings:

A.  Capacitor Charging Unit (Rectifier Unit)

The charging unit will be capable of  giving continuously variable Peak DC  Voltage up to 100 KV max. of either polarity to charge the generator capacitors to the required

value. This will be made compatible to work with Integrated Impulse Generator control  unit.  The  polarity reversal can be done by simple operations. The DC charging unit will  be  provided  with protection like zero-start interlocking, short circuit overload protection etc.

Technical Chart:

Rated Voltage                                            :   100KV peak max.

Rated max. charging current                 :    50mA max.

Duty Cycle                                                 :     Intermittent at 50mA & 20mA Continuous

The DC charging unit will be provided with protection like zero-start interlocking, short circuit/overload protection, door interlock etc.

Control circuit of the  integrated panel will charge the stage capacitor up to the set stage voltage  with  the following features:

• Charging Voltage setting
• Charging voltage display by Resistive High Voltage Divider and peak

B.  Resistive High Voltage Divider along with Peak Voltmeter

The Resistive High Voltage Divider will be an integrated part of the Charging Unit and the readout unit will be provided in the integrated control panel.

C.  Charging Resistors

Charging Resistors will be stacks of high value resistors to keep the charging current within safe limit.  Each resistor will be designed and fabricated suitably to work at the rated High Voltage.

D.  Generator Capacitors

The Capacitor Banks will be arranged along with the corresponding spark gaps aligned properly. The  spark gaps will be of spheres. The Capacitor Banks will be designed suitably to undergo several charging and discharging operations, stacked suitably with proper insulation co-ordination and field distribution. The value of the capacitor banks will be such so that on dead short circuit they will be capable of giving the required impulse energy.

E.  Triggering System

One composite triggering system for triggering the sphere gap assembly will be provided. Trigger operation will be controlled from integrated control panel.

F.  Wave shaping elements, Series resistance & parallel resistance

The resistors used for this will be capable of discharging  impulse  currents  corresponding  to  the required power. Each resistor will be designed to work suitably from the consideration of High Voltage. The resistors will be robust type.

G.  Potential Divider

A suitable Damped Capacitive potential divider will be provided to capture the  impulse  voltage  response. The low voltage section of the Potential divider will be connected to the impulse measure- ment unit i.e. a Digital Storage Oscilloscope (DSO).

H.  Integrated Impulse Generator Control Panel

The control panel will be provided with the followings:

• Mains ON/OFF switch, Fuse
• Indicating lamps
• Metering:
  1. Charging Voltage
  2. Peak Voltage
  3. Impulse measurement in DSO

• Triggering control- Motorised gap control of Sphere gap for Triggering from Integrated control pan-

Protection and safety arrangement

• Snap acting over current /short circuit tripping device for the DC HV charging
• Impulse generator will be equipped with the automatically controlled safety system which switches off the generator, shorts and grounds all capacitors upon power failure or  opening of safety  fence  or any other
• System will have adequate and reliable safety interlocks / devices to avoid damage to the system, work piece and the operator due to malfunctioning or
• Impulse Voltage Generator will include Spark-gaps & motor driven Safety Grounding Device.
• One grounding Rod with grounding wire of length 3 meters (approx) will be

J. Impulse Peak voltage & Wave shape measuring system

A Digital Storage Oscilloscope (DSO) of frequency bandwidth not  less  than 70MHz  will be provided with the Impulse Generator. The DSO will be provided with the fa-

cility to transfer the data to laptop through suitable PC interface or with the help of pen drive. The DSO will be supplied with suitable interface cable and software.

DSO with suitable probe will be able to display the peak value, rise time, Time to reduce to 50% of peak impulse voltage etc. covering the measurement over the entire range.

Note: Earthing Busbar will be available within the laboratory. Our equipment will be connected to that earth pit.

Making of Earth pit is out of scope of supply. 

DOCUMENTS:

Operation Manual, Works Test Report, Warrantee Certificate will be supplied along with the set.