The Megger VIDAR lets your team verify the integrity of the vacuum interrupter (VI) within an MV vacuum circuit breaker quickly and without dismounting the chamber. A suitable DC test voltage is applied directly to each pole of the open breaker; the result appears immediately via a green pass lamp or red fail lamp. No disassembly. No guesswork.
We supply the Megger VIDAR as authorised Megger distributors in Ireland. Calibration is available through our INAB-accredited laboratory in Portlaoise, with certificates traceable to national standards under ISO/IEC 17025:2017.
Note: The VIDAR was originally developed by Programma, a Swedish test equipment company subsequently acquired by Megger. The Programma name remains on the instrument panel, which is why both names circulate in the market. The current manufacturer and product owner is Megger.
Why vacuum interrupter integrity matters
Vacuum circuit breakers have real advantages over oil-filled or air-blast types, but those advantages depend entirely on the vacuum remaining intact. The problem is that it does not last forever.
Leakage starts after years or decades. When it does, the interrupters fill with air, the dielectric strength of the breaking chamber drops, and the breaker becomes unreliable. Critically, once a leak starts, the decompression process is typically rapid. By the time a problem manifests in service, you may already be past the point where the breaker can be trusted to interrupt a fault current safely.
Two other failure modes are worth knowing about. Contamination on the poles and on the exterior surface of the interrupter can degrade performance and make operation unsafe. And mechanical misalignment within the breaker assembly can reduce the effective distance between the poles to below what is adequate for reliable interruption. Neither is immediately obvious without testing.
The VIDAR was introduced in 1985 specifically to address this. Developed in close collaboration with leading vacuum circuit breaker manufacturers, it gives you a fast, reliable means of checking the condition of every VI in your fleet without taking the breaker apart.
The relationship between flashover voltage and vacuum condition
The VIDAR exploits a well-established physical relationship between the internal pressure of a vacuum interrupter and its ability to inhibit flashover. In a healthy interrupter, internal pressure is below 10⁻² mbar and dielectric strength is high. As vacuum degrades and air ingress occurs, the flashover threshold voltage drops in a predictable, measurable way.
This relationship permits indirect vacuum assessment by measuring the voltage threshold, without disassembling the circuit breaker. The VIDAR applies a selected DC test voltage across the open poles; if the VI can withstand it without flashover, the vacuum is acceptable. The datasheet references IEC 62271-1 (formerly IEC 694) and ANSI/IEEE C37.06 for guidance on appropriate test voltage selection for specific breaker types.
When to test vacuum interrupters
- Commissioning of new vacuum circuit breakers
- Scheduled maintenance and routine inspection programmes
- Following a suspected fault or any abnormal operation event
- Before returning a breaker to service after overhaul or repair
How the Megger VIDAR works
The VIDAR connects to each pole of the open vacuum circuit breaker via a permanently mounted high-voltage cable. A test voltage is selected from the front panel, both TEST safety knobs are turned simultaneously to apply high voltage to the breaking chamber, and the result is immediate.
- Green ACCEPTABLE lamp: the breaking chamber test result is positive. The VI is intact.
- Red DEFECTIVE lamp: the breaking chamber test result is negative. The flashover threshold voltage is too low, indicating degraded vacuum. The red lamp activates when leakage current through the interrupter exceeds 0.3 mA, as specified in the Megger VIDAR datasheet.
- Yellow CANCEL lamp: activates if the test interval exceeds one minute, if a second test is attempted within two minutes of the previous test, or if the high-voltage indicator malfunctions.
The two-hand safety control is not optional. Both TEST knobs must be turned simultaneously to apply high voltage; this is a deliberate design feature that prevents accidental energisation. A HIGH-VOLTAGE warning lamp is illuminated throughout any period when HV is present.
Why DC rather than AC for vacuum interrupter testing
International standards reference AC withstand tests as the primary method for high-voltage switchgear. For vacuum interrupters specifically, AC testing presents a practical problem: the inherent capacitance of the breaker assembly means a test set must be capable of supplying significant current to charge the capacitance on each half-cycle, making AC instruments bulky and poorly suited to field work or confined substation switchrooms.
DC testing sidesteps this entirely. The VIDAR follows ANSI/IEEE standardised DC test methods and is designed around the practical realities of field and shop floor use. A vacuum interrupter that passes a DC test will also pass an AC test. Where a result is borderline, Megger recommends repeating with reversed polarity to rule out field emission from a microscopic surface irregularity on a contact electrode.
Megger VIDAR specifications
All values confirmed from the official Megger VIDAR datasheet, Art. No. BR-29090, document reference VIDAR_DS_en_V03. Specifications are valid at nominal input voltage and an ambient temperature of +25°C.
| Parameter | Value |
| Standard test voltages (DC, switchable) | 10, 14, 25, 40 and 60 kV DC |
| Customised voltage option | Between 10 and 60 kV DC, determined at factory; default is 50 kV |
| Output ripple | Max 3% |
| Pass indication | Green ACCEPTABLE lamp (approved breaking chamber) |
| Fail indication | Red DEFECTIVE lamp (lights up if current exceeds 0.3 mA) |
| Interrupted test indication | Yellow CANCEL lamp |
| Standards compliance | ANSI/IEEE standardised DC test methods; test voltage guidance per IEC 62271-1 (formerly IEC 694) and ANSI/IEEE C37.06 |
| Mains input | 115/230 V AC (switchable), 50/60 Hz |
| Power consumption | 69 VA (max) |
| Protection | Overload cut-out |
| Operating temperature | -10°C to +50°C |
| Storage / transport temperature | -40°C to +70°C |
| Humidity | 5–95% RH, non-condensing |
| Instrument dimensions | 250 × 210 × 125 mm |
| Transport case dimensions | 460 × 430 × 210 mm |
| Weight (instrument only) | 6.9 kg (15.5 lbs) |
| Weight with accessories and transport case | 10.7 kg (23.6 lbs) |
| CE marking | LVD 2014/35/EU; EMC 2014/30/EU; RoHS 2011/65/EU |
| Art. No. | BR-29090 |
Kit contents
- VIDAR instrument
- Permanently mounted high-voltage cable set, 5 m (16 ft), for connection of test voltage and earth to the vacuum breaking chamber
- Ground cable
- Transport case (GD-00030)
Applications
The datasheet specifies the VIDAR for use in medium and high-voltage substations and industrial environments. In practice, it covers the full range of situations where vacuum circuit breakers appear: utility substations, industrial switchrooms, data centre electrical infrastructure, pharmaceutical plant MV distribution, and generating stations.
At 6.9 kg with a carrying case dimensioned at 460 × 430 × 210 mm, it is genuinely portable. A maintenance team can work through multiple breakers across a substation in a single day. The two-hand operation and self-contained design make it equally suitable for confined indoor switchroom environments and outdoor field work.
Typical use cases:
- Commissioning and acceptance testing of new vacuum circuit breakers
- Scheduled maintenance programmes for MV switchgear across utility, industrial, data centre, and pharmaceutical applications
- Pre-return-to-service testing following overhaul or repair
- Shop floor testing during refurbishment and fault diagnosis
Ordering and calibration
The VIDAR is available from Powerpoint Engineering as authorised Megger distributors in Ireland. Genuine product, full manufacturer warranty.
Important: the customised voltage option (between 10 and 60 kV DC, default 50 kV) is set at the factory and must be specified at the time of ordering. It cannot be changed after manufacture.
Calibration of the VIDAR is available through our INAB-accredited calibration laboratory in Portlaoise, Co. Laois, with calibration certificates traceable to national standards under ISO/IEC 17025:2017. If the instrument is out of calibration, it is out of service. Our laboratory turnaround times are designed with that in mind.
To order the Megger VIDAR or to discuss your vacuum interrupter testing requirements, call our technical team on 057 866 2162 or submit an enquiry online at powerpoint-engineering.com.
FAQ
What DC voltages does the Megger VIDAR support?
The VIDAR offers five switchable standard voltages: 10, 14, 25, 40, and 60 kV DC. One additional voltage between 10 and 60 kV DC can be customised to your requirements and is set at the factory when ordering; the default customised voltage is 50 kV. For guidance on selecting the appropriate test voltage for a specific breaker type, refer to IEC 62271-1 (formerly IEC 694) and ANSI/IEEE C37.06.
What does the red lamp indicate, and at what threshold does it activate?
The red DEFECTIVE lamp illuminates when the breaking chamber test result is negative, meaning the flashover threshold voltage is too low for the applied test voltage. Per the Megger VIDAR datasheet, the red lamp activates when the leakage current through the interrupter exceeds 0.3 mA. This is a confirmed product specification, not a guide figure. It indicates that the vacuum has degraded to a point where dielectric strength is insufficient for reliable operation.
Does the VIDAR comply with relevant standards for vacuum interrupter testing?
Yes. The VIDAR follows ANSI/IEEE standardised DC test methods, as stated in the Megger datasheet. Test voltage selection guidance is provided in IEC 62271-1 (formerly IEC 694) and ANSI/IEEE C37.06. The instrument carries CE marking under LVD 2014/35/EU, EMC 2014/30/EU, and RoHS 2011/65/EU.
Can the VIDAR be used without dismounting the vacuum interrupter?
Yes. One of the key practical advantages of the VIDAR is that the vacuum interrupter does not need to be removed from the circuit breaker assembly for testing. The high-voltage cable connects directly to the vacuum breaking chamber via large test clip connectors. This is the core reason the instrument is well-suited to both field maintenance and shop floor overhaul work.
Can the Megger VIDAR be calibrated in Ireland?
Yes. We offer calibration of the VIDAR through our INAB-accredited calibration laboratory in Portlaoise, Co. Laois. Calibration certificates are traceable to national standards under ISO/IEC 17025:2017. Call 057 866 2162 or contact us online to arrange.
Not exactly what you are looking for? Contact us with your exact requirements, we’re happy to help.
Megger (Programma) VIDAR Vacuum Circuit Breaker Tester Datasheet
For additional technical details about the Megger (Programma) VIDAR Vacuum Circuit Breaker Tester please refer to the product datasheet.
