The instrument is used to get the high voltage 0 to 12 KV/100mA as output from the 230VAC input. This is provided with built-in SF6 gas filled standard capacitor and useful for both grounded as well as ungrounded objects. Higher KV and current capacity power supply can be provided as per the requirements of our clients.

Features:

(A) Switch for three different types measurement:

1) UST - Ungrounded Specimen test - 3 combinations. This mode is used when the object under test is not grounded. This test provides most accurate results.
2) GST - Grounded Specimen test This mode is used when the object under test is permanently grounded. This test is used more often in outdoor installations & power systems
3) GSTG - Grounded specimen test with guard. 3 combinations. This mode is used for measuring the stray capacitances and separating it from basic measurement in GST mode.

(B) Indication:

Two 3½ digit digital panel meters one for voltage indication with 19.99 KV full scale and other for current indication.

Safety Features:

• Zero start control
  
• Open Ground Indication Lamp with Double Grounded Connection
  
• External Interlock
  
• HT Cut-off/on Overload
  
• HT On & Supply On Indication
  
• All Operating Controls at Earth Potential.
  
• Necessary Terminals & Sockets for connection to TD-1
  

Application Areas:

• H.T. & L.T. Power Capacitors
  
• Testing of H.T Transformers
  
• Power Systems
  
• Power Cables
  
• High Voltage
  
• Laboratories
  
• Generators
  
• Bushings
  
• Motors
  

Technical Applications:

Power Required: 230 VAC ± 10%, 50 Hz Standard Capacitor: Standard Capacitor is compressed SF6 gas filled type and is built into HV Power Source.
Capacitance: 100 pF ± 5%, actual value is indicated on capacitor.
Tan: Less than 0.00001
Rated Power: 1 KVA Max, 100mA Long Term
Test Voltage: 0 to 12 KV / 50 Hz

Electrical properties of insulating systems change due to age and Continuous electrical stress. By measuring electrical properties such as Capacitance and Tan d regularly it is possible to ensure the operational reliability of H.V. insulating systems and to avoid costly 2 Capacitance & Tan-Delta Test System [Model :- TD-1 ] breakdowns. PE Capacitance and Tan d test set comprises of C and Tan d Test System Model TD-1, High Voltage Power Source Model H-12/100 with built in standard capacitor, and set of cables. The compact design of the Bridge uses the principle of three winding differential transformer on a high permeability u metal core. The Bridge is contained in a sturdy metallic housing with u metal lining which shields it from external electromagnetic & electrostatic influences.

Features:

• High Sensitivity
  
• User Friendly
  
• Accuracy
  

Application Areas:

• High Voltage Sub-Stations
  
• Operation in Workshop
  
• Switch Yards
  
• Factories
  

Interface Suppression:

C & Tan d Test System has been specially protected with u metal sheets to keep away from the effect of external interferences. This makes the dimension exact in both inside as well as outside applications particularly in Switch yards. Phase reversal switch provided in the H.V. Power Supply effectively cancels interference/pick up by the object under trial in energized environment. For situation where the generation is extreme, and cannot be cancelled by phase reversal switch a separate three level. Interface suppression unit can also be given with separate C & Tan d adjustments.

Protection:

The bridge is provided with built in high voltage protection which protects the bridge & operator against failure of test object or standard capacitor.

Technical Specifications:

Capacitance Range: 1 pF to 0.1uF in three ranges with Cs=100pF
Accuracy: 0.1 Factor: - ± 1 % of reading ± 1 to 2 x 10-4
                      1 Factor: - ± 1 % of reading ± 1 to 2 x 10-3
                    10 Factor: - ± 1 % of reading ± 1 to 2 x 10-2
Tan d Range: 0.0001 to 11.1 in three ranges
Accuracy: ± 0.2%
Power Supply: Dry Batteries, 9 V x 2 nos.
Weight: LESS THAN 20 Kg.

This set is designed for Tan Delta measurement of Insulating Oil by using three terminal test cell with heating chamber. It gives Dielectric constant and Tan Delta (in percentage) directly on digital meter. The pressure voltage at which the measurements are to be made can be made and set as desired. Power basis is continuously variable up to 600 VAC which gives a highest stress voltage of 300V/mm in POWER Three terminal test cell.

Features:

• Direct readout of Dissipation Factor [Tan-Delta] in percentage.
  
• Sufficient Power Supply
  
• No tuning is necessary prior to every single reading.
  
• Results in higher testing speed and even semiskilled operators can use the equipment easily.
  

Technical Specifications:

Tan Delta Range: 0 to 19.99% FSD with resolution of 0.01% TanD.
Dielectric Constant Range: 0.2 to 10
Test Voltage: 0-600 VAC continuously variable or as ordered (Stress voltage 300 V/mm)
Indication: 3½ digit panel meter for tan d & 3½" taut band analogue panel
meter for voltage and Null indication
Power Supply: 230 VAC ± 10%, 50 Hz (110V, 60 Hz on request)
Warm Up Time: 5 minutes
Dimensions: 420 x 270 x 220 mm
Weight: 7 Kg (approx.)

These sets have facility for checking insulation resistance in the range of 1 meg ohm to 10 million meg ohm after one minute of charging. Intrinsic value of insulation resistance if required, even with capacitive loads. Separate push button controls and visual indicators for "Charge", and "Discharge" function are ideally suited for rapid and safe testing of components in a factory. Maximum output current has been limited to safe value to eliminate the risk of serious shock to operators. The instruments are available in two models as per specifications given overleaf.

Features:

• Completely solid state circuitry, hence drift free operation
  
• Fully protected against all overload and short circuits
  
• Suitable for testing ' EARTHED' Samples
  
• Tests as per I. S. I. recommendations
  
• Push Button Controls for rapid testing
  
• Suitable for testing insulation liquids
  
• Wide measurements range
  
• Guard Terminal provided
  

Technical Specifications:

Overload Protection: Fully protected against wrong selection of breakdown of components under test.
Power Supply: 230V AC ± 15%, 50 Hz Single Phase
Resistance Range: 1 Meg to 10 Meg in 6 ranges
Indication: 4¼ Taut Band Panel Meter
D.C Voltages:
For Model IRT-500:- 63V, 100V & 500V ± 2%
For Model IRT-1000:- 100V, 250V, 500V & 1KV ± 2%
Warm up time: One minute
Weight: Less than 7 Kg

Application Areas:

• Ceramic Capacitors
  
• Semi Conductors
  
• Plastic Capacitors
  
• Paper Capacitors
  
• Transformers
  
• Connectors
  
• Insulators
  
• Switches
  
• Motors
  

Heating Chamber, (OHC) with Three Terminal Oil Cell, is designed to heat the insulating oil up to the elevated temperature 0-150 º C in short time of 15-20 minutes. A potentiometer is provided for setting of temperature at required level. Heating chamber with oil cell for easier testing at required temperature fitted with thermostat & protection device to prevent shock hazards. Three Terminal oil cell is designed to test the Dissipation Factor (Tan-Delta) & Resistivity of the insulating oil.

Technical Specification of Oil Heating Chamber [OHC]:

Temperature Range: 0-150 º C
Indication: 31/2 Digital Panel Meter
Heating Element: Heating Coil
Power Source: 230VAC / 50Hz
Sensing probe: PT100

Technical Specifications of Three Terminal Oil Cell:

Made up of: S.S. & Teflon Spacers
Cell Capacitance: 55 Pico-Farad / ± 1 pf
Volume (Oil): 45-50ml.
Cell Constant: 620 Nominal
Electrode Distance: 2 mm

Compressed Gas Standard Capacitor is a set capacitor used as Capacitance standard in Bridge circuit for precision measurement of Capacitance and Tan d of high voltage test objects. The electrodes are made of polished metal and enclosed in a suitable cover for protection against dust and moisture. The compressed gas capacitor is filled with Sulphur Hexafluoride (SF6) under moderate pressure.

Features:

• Negligible dissipiation factor
  

Technical Specifications:

Accuracy of Capacitance: 0.1%
Operating Frequency: 50Hz 10%
Operating Voltage: Up to 12 KV rms
MODEL: Cs - 100
Capacitance: 100pf±5%
Tan d: <1 x 10 - 5
Temperature Co-efficient: <100 ppm
Dielectric: SF6
Max. Height: 370 mm
Max Diameter: 170 mm

This decade is specially designed for cross-checking the HV Capacitance & Tan-Delta Test System [Model TD-1] at 5KV. This decade having one capacitance tap along with three different Tan-Delta ranges.

Capacitance & Tan-Delta Measurement:

A dielectric loss testing program provides several important benefits. Periodic tests performed during the service life of the equipment can indicate that the insulation is either aging normally or deteriorating rapidly. Diagnostic tests may disclose the location of a fault, or the reason for failure. Insulation Resistance and Polarization Index is the most widely practiced and accepted test in identifying dryness/wetness of paper insulation. The life of transformer is mainly based or is very sensitive to amount of moisture content in paper insulation. This test gives information on aging condition or status of the insulation, moisture content in paper and hence is a very important test for identifying residual life.

Dielectric Loss Measurement (DLM) is in an insulation system is the power dissipated by the insulation when subjected to an applied alternating voltage. A high loss may indicate problems in the insulation structure. Normal aging of an insulating material will cause dielectric loss to increase. Contamination of insulation by moisture or chemical substances may cause losses to be higher than normal. Physical damage from electrical stress or other outside forces also affects the level of losses.

Winding Resistance Measurements:

The test is most effective when compared with such measurements from similar transformers, or previous test results or factory test data. This gives vital information for identifying abnormalities like loose connections and even broken strands. Since it is done at various tap positions, it also identifies any issues with OLTC such as high resistance joints. When compared with readings taken from each phase to ground

Turns Ratio/Voltage Ratio:

When the transformer is on open circuit, which is usually the case during field service, voltage ratio and turns ratio is considered equal for all practical purposes. The turn’s ratio test which is determined for all the taps with the tap changer for deenergized operation at one specific location such as nominal position helps in identifying part of the winding that is faulty, such as due to inter-turn shorts. This also helps in identifying problems that can otherwise lead to reduced secondary output, increased losses or voltage regulation issues.

Vibration & Phase Current Signature Analysis can be used to find
out following defects:

• Motor Rotor eccentricity Motor Rotor Bar Cracks
  
• Misalignment or Bend Shaft
  
• Motor Rotor Bar looseness
  
• Foundation defect / soft foot
  
• Electrical defect in motor
  
• Mechanical looseness
  
• Defective belt drives
  
• Unbalance in a Rotor
  
• Damaged Bearings
  
• Gear defects
  
• Resonance
  

Winding Resistance Measurements:

The test is most effective when compared with such measurements
10 RLA/Testing of H. T. Motor/Generator from similar motor/generator, or previous test results or factory test data. It gives the full information of abnormalities like loose connections, broken strands etc. It even identify other issues like unbalance that result in overheating & circulating events.

Insulation Resistance Polarization Index [IR/PI]:

Insulation Resistance and Polarization Index is the most commonly Practiced and accepted test in identifying dryness/wetness of paper insulation. The life of motor/generator is mainly based or is very sensitive to amount of moisture content in paper insulation. This test gives information on aging condition or status of the insulation, moisture content in paper and hence is a very important test for identifying residual life.

Dielectric Loss Measurement (Capacitance & Tan-Delta):

A high loss may indicate problems in the insulation structure. Normal aging of an insulating material will cause dielectric loss to increase. Contamination of insulation by moisture or chemical substances may cause losses to be higher than normal. Physical damage from electrical stress or other outside forces also affects the level of losses. A dielectric loss testing program provides several important benefits. Periodic tests performed during the service life of the equipment can indicate that the insulation is either aging normally or deteriorating rapidly. Diagnostic tests may disclose the location of a fault, or the reason for failure.

We at Power Electronical are also engaged in manufacturing, maintenance & calibration services of insulation testing instruments. As well, by an experience we have entered in Transformer Oil Testing Services as per requirement of NABL - ISO / IEC-17025: 2005[E] & RLA of the Power Transformer.The Physical & Chemical test are carried out as per IS 1866:2000 and Dissolved Gas Analysis as per IS 9434:1992. For the sampling of oil from transformers mostly air tight Metal cylinders (Stainless Steel) can be used effectively. To obtain a representative sample, it is necessary to use the proper sampling technique. (IS 6855:2003).

Application Areas:

• Transformer - CT / PT

Dissipation Factor (Tan-Delta) is one of the most influential off-line nondestructive diagnostic tool to check the state of solid insulation of various high voltage equipment. Capacitance and Tan-Delta values obtained on new insulation are treated as standard readings. Then by measuring and comparing the periodical readings of the Capacitance and Tan-Delta of the insulating material with the benchmark readings, one can know the rate of deterioration of health of the insulation.

By calculation of the rate of deteoration we can:

• Repair the insulation before actual flashover, saving high cost of replacement of material which will reduce the inventory as well as delay in procurement at the last minute.
  
• After repair, quality of insulation can be checked before returning the equipment to service.
  
• Predict the future unexpected breakdown of the insulation of HV equipment.
  
• Plan the maintenance schedule.
  

When to check Capacitance & Tan-Delta:

• Frequency of testing depends on environmental conditions. More humidity, temperature, pollution would require frequent measurement of Tan-Delta.
  
• In service & will be depend on rate of change of Tan-Delta Vs Voltage Vs Time (Month/ Year)
  
• Frequency of testing depends on history of past failures on same machine.
  
• During manufacturing process preferably at each stage.
  

We Provide Calibration services for Electro-Technical Field Instruments :

• Digital /Analouge Multimeter
• Digital / Analouge Earth Tester
• Digital / Analouge Insulation Resistance Tester
• High Voltage Tester
• Clamp on Meter
• High Voltage Probe
• Capacitance & Tan Delta
• Brake Down voltage Tester
• Temperature (0 to 150 Degree)