CAL1, CAL2, and CAL3 Calibration Impulse Generators

Impulse generators with excellent impulse properties thanks to a unique design concept

Power Diagnostix’s instruments of the CAL series are impulse generators for the calibration of partial discharge (PD) measurement setups in the high frequency (HF) and ultra-high frequency (UHF) range as well as for RIV measurement setups

Conformity to international standards

Excellent operating time

Easy to use

Convenient connection

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About the product

ICM series Accessories: Calibrators

Partial discharge measurement is a useful tool to analyse the insulation of high voltage components. However, partial discharges can usually not be measured directly, just the apparent charge of such signals are captured by the measuring instrument. Therefore, a calibration of the whole measuring system is required. To do this, short-duration current pulses of a known charge magnitude are injected into the system, and from this, a scale factor can be calculated for later partial discharge (PD) measurements.

Power Diagnostix offers a broad range of calibration charge injectors suitable for the calibration of PD measurements. The appropriate choice of a calibrator depends on the range of typical charge values of the PDs being measured. PDIX calibrators are suitable for calibrating test setups for the following assets:

Cables
Transformers
Rotating machines
Gas-insulated switchgear

Additionally, the calibrators of the CAL1 series can also be used for time domain reflectometry in cables to determine the cable length and the location of joints.

The instruments of the CAL series can be equipped with optional features to suit a broad range of applications. Available options are:

Suitable for 50 and 60 Hz, switchable
Double pulse with adjustable time delay (for CAL1 series)
Remote power input for the supply by an external 12 to 24 V DC voltage
Selection switch for single pulse or continuous pulses (allows the output of manually triggered single pulses)

Every PDIX calibrator comes with a set of clamps, plugs, adapters, and pre-assembled cables for the comfortable connection of the calibration impulse generator to the measurement setup. The ready-to-use sets include everything for a quick and convenient connection of the device to the specific test setup.

Troubleshooting

The calibration pulse is not visible on the display of the measuring instrument

First check that the calibrator is still on. The calibrator will shut off automatically after about 15 minutes without having one of its buttons pushed. Check that the low battery indicator is not visible on the LCD of the calibrator.
The calibration pulse setting might be too weak for the test setup. Try increasing the magnitude of the calibration impulse applied to the test setup.
Sometimes the calibration pulse is lost if the high voltage power supply is connected to the test setup when the calibration is performed, even if the high voltage supply is completely powered off. Ensure that the power supply is not earthed during calibration. Try physically disconnecting the high voltage supply from the test object during the calibration process. The calibrator is then only connected via the quadrupole of the test object and the coupling capacitor (if present).

The battery of my calibrator is low/empty? How do I change it?

Power Diagnostix’s calibration impulse generators are equipped with long-life lithium batteries that ensure an operation time up to 200 hours. Just in case you need to replace the battery anyway, Power Diagnostix has prepared an instruction document for the battery change. Please refer to the “User guides and documents“ section below.

FAQ / Frequently Asked Questions

How should background noise during calibration be taken into account?

If the calibration pulse is not much higher than the background noise, the random noise signal is added to the calibration signal (noise modulation). This results in a pulse, which is higher than the calibration pulse and usually not stable in magnitude. Since the Power Diagnostix's measurement instruments always take the peak value for calibration, the exact calibration pulse plus the random noise signal will be taken. This leads to a wrong calibration. Measuring a higher, known calibration pulse will help to recognise and avoid this behaviour.To avoid misleading calibration, it shall be ensured that:• The background noise is minimised• The calibration pulse is much higher than the background noise• The noise level is known and considered

What is the correction factor, and when do I need it?

The calibrator including its injection capacitance (Ci) has to be removed after calibration and, hence, the measurement setup is (slightly) changed. To keep the impact of this removal as small as possible, Ci should be small versus the specimen’s capacitance (Ci should be smaller than 0.1 × Cx), otherwise a correction factor has to be taken into account in order to compensate for the missing injection capacitance. Power Diagnostix’s measuring instruments can automatically calculate the correction factor (please refer to the user guide of the respective instrument), but in most cases this is not necessary.

How often should calibration impulse generator be calibrated?

To ensure a reliable PD measurement, annual calibration of the impulse generator is recommended.