MEGGER
AC insulation testing
AC insulation tests are a popular response to the increasingly demanding industrial, power and domestic marketplaces. Insulation materials have had to become more efficient to keep up with demand; more efficient equipment requires less insulation material to meet the minimum acceptable value of insulation resistance. In turn, cables have become smaller and lighter. However, under certain higher stress testing conditions such as DC testing, cables like Crossed Linked Polyethylene (XLPE) can quickly degrade.
AC insulation testing provides the ideal solution to testing these lighter cables. AC insulation testing better simulates the day-to-day stresses undergone by power systems, including frequencies like 50/60 Hz, without causing the insulation breakdown common in DC testing. Additionally, AC testing won’t affect XLPE cables when used for over-potential testing, to an agreed acceptable insulation resistance value.
Because AC current alternates, many more parameters can be measured while an AC test is being conducted. These extra parameters include Power factor and Tan Delta values, as well as modern diagnostic techniques such as Sweep Frequency Response Analysis, Digital Frequency Response and Frequency Domain Spectroscopy. AC insulation testing may therefore be used in ‘condition monitoring’ of AC-powered apparatus.
However, AC dielectric tests must supply both reactive and resistive currents to the items under test resulting in larger equipment in size than DC testing devices. Lower frequency AC testers can offer smaller sizes, making them more applicable to field work.
50 and 100 kV AC Dielectric Tester
- Permits ANSI A92.2 for tests on aerial bucket trucks
- 50-kV tap with doubled output current for ANSI A92.2 bucket liner testing
- Output current meter, with guard circuit, for ANSI A92.2 leakage current measurements
The 50/100 kV AC Dielectric Test Sets are ac high-voltage sources for testing electrical insulation. The standard system includes a control/instrument cabinet, a high-voltage transformer assembly and all necessary cables including ground and input power.
These test sets consist of general-purpose ac high-voltage sources suitable for dielectric withstand (high-potential) testing of all types of electrical insulation. They also permit guarded leakage current measurements and are suitable for use with capacitance and dissipation factor bridge systems to measure insulation power factor.
CB100- POWER FACTOR TESTER
- Permits ANSI A92.2 for tests on aerial bucket trucks
- 50-kV tap with doubled output current for ANSI A92.2 bucket liner testing
- Output current meter, with guard circuit, for ANSI A92.2 leakage current measurements
The 50/100 kV AC Dielectric Test Sets are ac high-voltage sources for testing electrical insulation. The standard system includes a control/instrument cabinet, a high-voltage transformer assembly and all necessary cables including ground and input power.
These test sets consist of general-purpose ac high-voltage sources suitable for dielectric withstand (high-potential) testing of all types of electrical insulation. They also permit guarded leakage current measurements and are suitable for use with capacitance and dissipation factor bridge systems to measure insulation power factor.
CDAX 605- HIGH-PRECISION C AND DF MEASUREMENT INSTRUMENT
- High accuracy and wide measurement range
- Automatic measurement process
- Measures capacitive, resistive or inductive test objects
- High accuracy ratio measurements
- Works with any standard capacitor or resistor value without any recalculations
- All standard UST and GST configurations
CDAX 605 is designed for laboratory, production line or field testing of electrical equipment insulation and insulating materials as well as e.g. calibration of CCVTs and other ratio devices. A test set with unique high accuracy for the most demanding applications.
DELTA4000 Series- 12 KV INSULATION DIAGNOSTIC SYSTEM
- Power factor test set
- Automatic and manual operation
- Accurate and repeatable measurement results with high noise suppression
- Lightweight, rugged two-piece design
- New built-in intelligent temperature correction
- New automatic voltage dependence detection
DELTA4000 series is a fully automatic 12 kV insulation power factor / dissipation factor (tan delta) test set designed for condition assessment of electrical insulation in high voltage apparatus such as transformers, bushings, circuit breakers, cables, lightning arresters, and rotating machinery.
Two configurations make up the series:
- DELTA4110 with external computer (not included) consists of the DELTA4100 control unit and DELTA4010 high-voltage unit
- DELTA4310A touch display interface comes with onboard computer, PowerDB software and printer and allows connection to and control of MWA300, TTR300/310E, MTO300, MLR10 and some Megger insulation resistance instruments.
HPA100AC and HPA130DC- 100 KV 50 HZ TEST SYSTEM
- Powerful test and burning system
- Continuous testing with AC voltages up to 100 kVrms at 5 kVA
- Own noise-level below 1 %
- Built-in overcurrent protection
- DC testing up to 130 kV with optional rectifier
HPG35, HPG50, HPG58 and HPG78- AC HV TEST SETS
- HPG 35, AC testing up to 35 kVrms
- HPG 50 / 58 AC testing up to 50 / 58 kVrms
- HPG 78, AC testing up to 78 kVrms
The AC voltage test sets HPG 35 to 78 are suitable for 50 Hz AC testing of test objects with a low capacity. In addition to 50 Hz AC testing these units can also be enhanced to a DC test set, (see DC-Test Systems).
Typical application areas:
- Testing of switchgear
- Testing of current-transformers
- Testing of MV plant/ component testing
HPG50-D, HPG70-D and HPG80-D- DC AND AC HV TEST SYSTEM
- HPG 50-D, AC testing up to 35 kVRMS/ DC testing up to 100 kV
- HPG 70 / 80-D, AC testing up to 50 / 58 kVRMS / DC testing up to 140 / 150 kV
Typical application areas:
- Testing of cables
- Testing of switchgear
- Testing of current-transformers
- Testing of MV systems
HPG50-H, HPG70-H, HPG80-H and HPG110-H- DC AND AC HV TEST SYSTEM
- HPG 50-H, AC testing up to 35 kVRMS / DC-testing up to 50 kV
- HPG 70 / 80-H, AC testing up to 50 / 58 kVRMS / DC-testing up to 70 / 80 kV
- HPG 110-H, AC testing up to 78 kVRMS / DC-testing up to 110 kV
The High Voltage test sets HPG 50 to 110-H are suitable for 50 Hz AC-testing (35 to 78 kVRMS) and DC-testing up to 110 kV. The HPG 50 to 80-D are suitable for 50 Hz AC testing (35 to 58 kVRMS) and DC testing up to 80 kV*. The HPG test systems consist of two separate units: the control unit and the high-voltage unit. This separation enables the operator to use the test set on-site without any complications.
Typical application areas:
- Testing of cables
- Testing of switchgear
- Testing of current-transformers
- Testing of MV systems
IDAX300 and IDAX350- INSULATION DIAGNOSTIC ANALYSER
- State-of-the-art measurement of moisture content, tanδ and oil conductivity using DFR (Dielectric Frequency Response)
- Easy-to-use: Software with automated measurement flow and analysis of test results
- “Traffic light” interpretation of test results
- Dedicated test procedures for power transformers, bushings and current transformers
- Automated individual temperature correction (ITC) for accurate comparison with reference data/tests
- Reliable measurements even in high-interference environments
- Interfaces to high voltage amplifiers
- Versions with or without on-board computer
IDAX is an insulation diagnostic instrument based on DFR (Dielectric Frequency Response), also known as FDS (Frequency Domain Spectroscopy). DFR technology is an established test procedure in laboratories that in an innovative effort by Megger has been adapted for field use in the IDAX range of instruments.
In short, DFR is the measurement of capacitance and losses (dissipation factor (tanδ) or power factor) over multiple frequencies. The measured DFR curve is dependent on insulation geometry, moisture, oil conductivity and temperature and through advanced fitting to a reference material model moisture content, predominantly in solid insulation, oil conductivity at 25°C reference temperature and tanδ at 20°C reference temperature can be calculated. In the calculations ITC (Individual Temperature Correction), another important Megger innovation is used to translate test data from the test object temperature to the reference temperatures. It the latest release, the IDAX SW incorporates a new ITC corrected frequency sweep specifically designed for assessment of instrument transformers and bushings. IDAX is exceedingly easy to use with an automated test flow and presentation of results in an easy to understand “traffic light” manner.
The IDAX DFR method is now part of international guides and standards e.g. Cigre TB 254, Cigre TB 414, Cigre TB 445, Cigre TB 775, IEEE C57.152-2013, IEEE C57.161-2018
IDAX is available in multiple versions:
- IDAX 300 – A compact and light 3-channel input (red, blue and ground), 3 terminal (generator, measure and guard) and one ammeter instrument for use with an external computer that runs the IDAX diagnostic software.
- IDAX 300/S – As IDAX 300 but with two ammeters for two simultaneous measurements.
- IDAX 350 – As IDAX 300/S but housed in a rugged and waterproof case together with an onboard computer that can also be used to control other Megger instruments.
T22/1 - A.C. HIGH VOLTAGE TEST SYSTEM
- Continuous testing with AC voltages up to 75 kVrms at 1 kVA
- Expandable with a second transformer for testing up to 150 kVrms
- Built-in overload protection
- DC testing up to 80 kV with optional rectifier
The AC Voltage Test Set T 22/1 is a portable test set consisting of two separate units: the control unit and the high-voltage unit. This division enables the operator to use the test set on site without transport aids. The test set can be equipped with a rectifier attachment for DC voltage testing up to 80 kV.
T22/13B - HIGH POTENTIAL TESTER (HIPOT)
- 15 kV and up to 25 A Burn current
- Short circuit proof
- Display of output current and voltage
- Pulsed voltage for earth fault location
The 15 kV burn unit T 22 / 13 B is a very powerful high voltage burn unit for system integration, but also available as portable stand-alone unit.
The high output power and the short circuit proof construction permit in almost all situations the easy conversion of high resistive and intermittent faults into low resistive faults. The resonance burning technology allows a comparatively smaller but very powerful burn unit.
VAX020 - 2 KV HIGH VOLTAGE AMPLIFIER FOR IDAX300
- Separate high voltage amplifier enables capacitance and dissipation factor measurements at 2 kV test voltage
- True and proven DFR/FDS technology for highest performance
- Large frequency range, DC to 1 kHz
- Compact design, weight < 5 kg
VAX020 expands the IDAX300 test voltage range from 200 V to 2 kV. This improves the capability to perform accurate measurements in extreme high interference environments e.g. HVDC substations.
Besides 50/60 Hz capacitance and dissipation factor (power factor) measurements, the application gives valuable information about the general condition of any high voltage insulation by measuring its dielectric response. The technique is also capable of assessing the moisture content in oil/paper insulation systems.
