Description

“NTPL” MAKE PARTIAL DISCHARGE TEST SET UP FOR 33KV CABLES WITH 100kV/10A-50kV/20A AC SERIES RESONANCE HV SOURCE

“NTPL” make AC High Voltage source is capable of giving continuously variable High Voltage from almost zero to max. rated voltage considering that the minimum capacitance load is connected as test object. This Series Resonance type AC HV source is based on resonance feature of electrical circuit, thereby being almost free from harmonic disturbances and also consumes much reduced power from the mains supply and the huge inrush of current can be avoided in case the object under test fails during testing.

The only limitation of this system is that you need a minimum capacitance as load.

Technical Data

• Rated input            :    415V      145A   60kVA                   50Hz      Active Nature
• Rated output 1       :    100kV   10A     1000kVA              50Hz      Reactive Nature
• Rated output 2     ：   50kV     20A    1000kVA               50Hz      Reactive Nature
• Load duty cycle: maximum operation time is 1 hour under 50％ rated load.
• Nominal quality factor Q (designed value) ：Q=20
• Inductance regulation range of reactor will be as below to cater corresponding cable capacitances.
  50kV    7.96H～169.04H   Minimum and Maximum Load (Cable) Capacitance 0.063μF～1.27μF
  100kV    31.85H～676.15H   Minimum and Maximum Load (Cable) Capacitance 0.0159μF～0.318μF 

Special Features:

Accuracy of voltage measure：≤±1％（as to IEC60060-1, the precision shall be ensured within range of 10-100%）

• PD level when system is operated with no load: PD≤2pC under 100% rated voltage (at HV filter output end)

Minimum Recommended Load Capacitance Required:  0.095uF for 50 KV and 0.023uF for 100KV.

• Output voltage variation: By means of motor driven arrangement of voltage regulator.
• Operation Control: Automatic control (programmable test voltage, test duration, rate of rise, ramp and

        dwell control, automatic controls of motorized voltage regulator).

• Resonance Control: By Motorized operation and can be done in auto as well as in manual mode. Even

        in auto mode facility for manual control is provided for fine tuning.

• Over load Tripping : Since in the series resonance system the voltage collapses in case of breakdown of job under test possibility of huge short-circuit current is ruled however an overload Tripping will be provided for the exciter Transformer.
• Over Voltage Indication & Interlock Protection provided. 

Discharge Free AC HV Test source will be in multiple units i.e.

1. PC Based Control & Measuring Unit [100kV/10A-50kV/20A AC SERIES RESONANCE HV SOURCE, TYPE:ACSR100K10A-50K20A-PDF]
2. Voltage Regulator
3. Isolation Transformer 60KVA
4. LV Filter Unit
5. HV Exciter Transformer
6. AC HV Variable Series Reactor
7. HV Filter
8. Coupling Capacitor cum Potential Divider

All the above units will be provided with wheels and lifting arrangement for easy movement. 

1. PC BASED CONTROL & MEASURING UNIT: [TYPE:ACSR100K10A-50K20A-PDF]

• Power Mains ON – OFF operation is done by means of Switch Disconnector with Fuse unit along with ‘MAINS ON’ lamp indication.
• ‘Control ON-OFF switch along with ‘CONTROL ON’ lamp indication & fuse protection.
• ‘HT ON-OFF’ push button along with ‘HT ON’ lamp indication and ‘EMERGENCY OFF’ mushroom type push button.
• Isolation transformer for control operation, auxiliary supply to meters and power supply for electronic PCBs.
• Once the Resonance is achieved INCREASE/DECREASE circuit to control motor operated Voltage Regulator. The regulator will rotate to increase the output test voltage at preset speed up to the preset test voltage level.
• HV test level can be adjusted at any value between 10% to 100% of the range selected. After reaching the set voltage the Regulator will stop and one lamp will indicate such event.
• Electronic control circuitry will be capable to control…………..
• Rate of Rise : At the variable rate ie, slow, medium and fast
• Rate of Fall: At the fastrate .
• Dwell Time :   a) Automatic Mode: From 30 Sec. to 300 Sec. in steps of 30 Sec
  b) Manual Mode : Operator specific within specification limit.

METERING:

This will indicate the following:

• Output HV
• Current at the HT side
• Rate of Rise
• Test Duration
• Protective status/error message ( if any, Over Voltage, Over Current, Regulator Over Run, Trip )

Since all the above parameters will be displayed in HMI panel interfaced with micro-controller based circuit so no panel meters are required.

PROTECTION & INTERLOCK:

• The resonance system is intrinsically short circuit protected as the voltage drops immediately when there is any failure in the insulation of the equipment under test. An automatic tripping mechanism for protecting the HV exciter Transformer against overloading is provided. The tripping mechanism can be adjusted at different values as mentioned above. In addition to that, a protective device against overloading will be provided in the regulator output side and that will be set at maximum permissible loading in the regulator output side. High Voltage will be switched OFF on tripping.
• Fast acting relay will be provided which will actuate when HT current exceeds the per-set max. permissible limit. This tripping mechanism can be adjusted at different values as mentioned before.
• In addition to that, a CT operated fast acting protection will be incorporated with respect to max. LT current corresponding to max. rated capacity of the test system. This protective circuit when actuates will trip Off the HV output.
• Zero start interlocking will be provided to ensure that the HV circuit cannot be energised unless the regulator is initially kept or brought back to zero position.
• The HV Test Equipment & sample under test may be kept within a Screened room i.e. Faraday cage. Enclosure interlocking will be provided i.e. high voltage circuit cannot be energised unless the door of the enclosure is closed.
• In case the output voltage crosses the maximum rated value a lamp & a buzzer will indicate over voltage and the increase mode circuit will not function further, even if ‘PRESS TO INCREASE’ push is pressed.

The whole control circuitry will be housed within a sheet metal cabinet properly powder coated.

2. VOLTAGE REGULATOR:

Continuously variable motorized voltage regulator of suitable capacity & control circuitry will be provided to increase & decrease the test voltage. Minimum & maximum position interlock will be    provided so that limit switch will automatically disconnect Increase/Decrease circuit of motor connection at maximum and minimum position respectively.

Over voltage protection i.e. in case the output voltage crosses the maximum rated value a buzzer will indicate over voltage and the increase mode circuit will not function further, even if ‘PRESS TO INCREASE’ push is pressed.

3. ISOLATION TRANSFORMER:

This will isolate LT Power supply required for Partial Discharge Test set- up from conductive noise of Mains Power supply system.

The transformer will be provided with electrostatic shielding of proper configuration.

Primary Voltage                              :              415 volts, single phase, 50Hz, AC.

Secondary Voltage                          :              415 volts, single phase, 50Hz, AC.

Capacity                                            :              60KVA

Cooling                                              :              Oil natural.

Duty                                                   :              Same as HV source.

Secondary terminations will be provided with guard arrangement.

4. LV FILTER Unit:This Line filter unit is provided mainly to filter out spurious conductive noises introduced from Mains Power   Supply.

5. HV EXCITER TRANSFORMER:HV Transformer used in the test set will be oil natural cooled type and of suitable capacity. One end of the high voltage winding will be connected to the earth potential through a CT operated Ammeter & protective device while the other end will be connected to the lower end of HV Series Reactor.

6. AC HV VARIABLE SERIES REACTOR:This AC HV Variable Series Reactor used in the Test set will be oil natural cooled type and of suitable capacity. One end of the HV winding will get connection to the HV output of the exciter transformer while other end will remain floating as HT output terminal. Minimum & maximum position interlock will be provided so that limit switch will automatically disconnect circuit of motor connection at minimum and maximum gap position respectively.

7. HV FILTER:HV Inductive Filter will be connected after the HV generator to reduce the discharge noise in the final HV output.

8. HV COUPLING CAPACITOR CUM POTENTIAL DIVIDER WITH MATCHED IMPEDANCE:There will be a Capacitive HV Potential Divider provided with low voltage arm.
   A UHF connector with coaxial cable is used to connect a metering circuit (provided in the panel) to indicate High Voltage.
   Rated max working voltage – 100KV AC rms.
   Capacitance – 1000pF (nominal)
   Discharge free i.e.<2pC up to at least 80KV voltage level.
   The capacitor will be provided with corona guard.
   HT terminal will be provided with anti-corona metallic ring of adequate diameter to facilitate uniform stress free charge distribution. 

1. PARTIAL DISCHARGE METER WITH EXTERNAL PD CALIBRATOR [TYPE – PDNT04-XCLBR]The application of Partial Discharge testing is growing wider during the last four decades and presently PD testing is considered one of the most useful non-destructive means for assessing the quality of High Voltage Transformer, motors, cables etc. used in generation & distribution of electric power. The PD Meter is to be connected to “NTPL” make Matched Impedance.

 Technical Features:

• PD discharge level measurement in Pico coulomb.
• Broad band detection of discharge pulses.
• The PD Meter will have connectivity with Digital Storage Oscilloscope (DSO) that can be connected to observe partial discharge in time domain as well as in phase space i.e. in elliptical base.
• Provided with DSO of not less than 60MHz Bandwidth.

Technical specification:

Mains Power Supply                                   :              230 volts 50Hz, single phase AC.

Measuring Range                                         :              0- 2000pC.  Effective measurement range 0-50pC

Measurement Bandwidth                           :              Lower cutoff @ 30KHz.

Upper cutoff @  300KHz.

Phase resolved Gating                                 :              Phase resolved gating facility is provided to reduce interference by

unwanted noise.

PD meter indication                                     :      Digital LCD type.

Operating temperature range                    :              0 – 45⁰C

Humidity Range                                            :              95% non condensing.

EXTERNAL PD CALIBRATOR:

This is an offline External calibrator to get standard pulses of 5pC, 10pC, 20pC, 50pC.

Features:

• Supply ON/OFF switch.
• pC Selector along with Off mode

Interconnecting cables: A set of interconnecting shielded coaxial cables between Capacitor, Discharge meter, Matched impedance unit etc. will be provided. 

“NTPL” MAKE PARTIAL DISCHARGE METER WITH EXTERNAL PD CALIBRATOR TYPE – PDNT04A-XCLBR 

The application of Partial Discharge testing is growing wider during the last four decades and presently PD testing is considered one of the most useful non-destructive means for assessing the quality of High Voltage Transformer, motors, cables etc. used in generation & distribution of electric power.

The PD Meter is to be connected to “NTPL” make Matched Impedance.

Technical Features:

• PD discharge level measurement in Pico coulomb in Digital Readout.
• Broad band detection of discharge pulses.
• The PD Meter will be provided with PC based Digital Storage Oscilloscope (DSO) module that can be connected to PC through communication cable to observe graphical response of partial discharge in time domain as well as in phase space i.e. in elliptical base.
• PC/Laptop as mentioned above is out of scope of our supply, however necessary software will be provided.

Technical specification:

Mains Power Supply                       :              230 volts 50Hz, single phase AC.

Measuring Range                            :              0- 2000pC.  Effective measurement range 0-50pC

Measurement Bandwidth             :              Lower cutoff @30KHz.

Upper cutoff @300KHz.

Phase resolved Gating                   :              Phase resolved gating facility is provided to reduce interference by

unwanted noise.

PD meter indication                      :             Digital LCD type.

Operating temperature range      :              0 – 45⁰C

Humidity Range                             :              95% non-condensing.

EXTERNAL PD CALIBRATOR:

This is an offline External  calibrator to get standard pulses of 5pC, 10pC, 20pC, 50pC.

Features:

• Supply ON/OFF switch.
• pC Selector along with Off mode

Interconnecting cables: A set of interconnecting shielded coaxial cables between Capacitor, Discharge meter, Matched impedance unit etc. will be provided.

Note: An important feature incorporated in the Test setup is protection of PD meter during pre-stressing of the sample under test. PD measurement by default is kept disabled during this period and can be enabled at a point when PD level is to be measured. This can be controlled from the PD measurement unit.

In case the HV set up is integrated as part of PD test set up the HV measurement is clubbed with Coupling Capacitor cum Potential Divider.A protection interlock will be provided such that HV cannot be energized during calibration mode of PD meter is selected.

ACCESSORIES:

Discharge ROD: In AC High Voltage test, after testing, the device under test is normally discharged through transformer winding. However, for device under test having large capacitance a discharge rod may be used and hence it is provided with the set.

HV Connectors:

Discharge free connectors will be used for HV interconnections. These will be provided with stress free end connectors which can be used to interconnect different units viz. HV Transformer, HV Potential Divider, job under test etc.

POWER & INTERCONNECTING CABLES:

Power cables, interconnecting cables along with suitable plug & sockets are provided.

Documents:

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

OPTIONAL AT EXTRA COST:

SCREENED ROOM (FARADAY CAGE) WITH SUITABLE EARTHING SYSTEM:

For best results during measurement of PD the HV Transformer with all HV accessories and sample under test should be kept inside a Faraday cage (Screened room). Depending on the max, dimensions of your equipment under test the approximate size of the FARADAY cage will be finalized.

The Faraday cage will be made of prefabricated panels with two layer metallic sheet separated by insulation layer.  These pre-fabricated panels are mounted on mild steel structure with angles and sheets of different geometrical shapes.

Doors: There will be provided one door either Sliding or Single Leaf Door.

The doors will have suitable contacts with the main cage so that the doors when closed form a continuity of the cage so far as electromagnetic shielding is concerned.

EARTHING SYSTEM

An efficient grounding, isolated from the mains ground is mandatory for PD test setup. The isolated screen room is to be kept tied to this ground. Isolated Earth connection should be made ready by the user before commissioning of Test setup. Earthing is out of scope of our work. An isolated floor (With layer of Insulating Sheet) should be made ready by you before commissioning of the Faraday cage.

We provide guidance in making isolated ground once the order is placed on us.