Testing circuit breakers with the CIBRE analyser series

A circuit breaker is the main line of defence in any MV or HV installation. It must close when required, and open within milliseconds when a fault occurs. Between those two moments: contacts, springs, dampers, insulating gases, auxiliary contacts and operating coils. If one of those links degrades unnoticed, the worst-case scenario is a breaker that opens too late — with all the consequences for protection coordination and liability.

A good analyser tells you whether it works — and how well. This article covers what to measure, why it matters and which model from the HighTest CIBRE analyser series suits which type of work.

A complete circuit-breaker diagnosis covers four measurement domains: contact timing, motion (mechanical movement), voltages on auxiliary contacts, and coil current during opening and closing. Together, those four datasets give you the full picture of the breaker’s electrical and mechanical health.

1. Contact timing

The primary test. You measure how quickly the main contacts open or close and whether the three phases operate synchronously. The CIBRE analyser has measurement functions for O (Open), C (Close), O-C, C-O and O-C-O. Alongside the main contacts, you also measure the insertion resistor contacts, which briefly switch in a damping resistor before the main contact to limit transients — the timing between resistor and main contact must be within spec.

2. Motion analysis

The mechanical side. With a linear or rotary encoder on the operating mechanism, you record position as a function of time. From that follow three key metrics: speed (m/s at the moment of contact touch), stroke (the total movement) and bounce (brief oscillation after the end position). A slow or bouncing breaker indicates wear, contamination, or a weakened spring — often before timing is out of spec.

3. Voltage measurements on auxiliary contacts

V1 (analogue 0–250 V DC or ACpeak) and V2 (presence/absence detector 24–300 V DC or ACpeak) capture the switching behaviour of auxiliary relays and signalling contacts. Important for verifying the logic around protection and interlocking, and at FAT to demonstrate that the auxiliary circuits are correctly wired.

4. Coil current logging

The current through the operating coil itself, measured in the 0–20 A DC range (bandwidth 5 kHz). The current waveform on energising shows how the coil armature moves and when the latch releases. The moment the main contact opens or closes comes from the contact timing. Deviations in the coil-current curve indicate coupling problems, dry bearings, or a disturbed damper — diagnostic information you don’t get from timing alone.

Not every test moment requires the same depth. The three most common situations:

Commissioning

Bringing a new breaker into service. Here you want to measure everything and record the values as a baseline for the maintenance trajectory ahead. Contact timing, motion, voltages on auxiliary contacts, coil current — all in a single test session. For three-phase MV and HV breakers, you want to measure all three phases simultaneously to document synchronicity.

Periodic inspection

Maintenance check every few years (depending on breaker type and load). Here you compare against the baseline. Contact timing and motion are the main indicators; coil current logging signals the onset of mechanical wear. The manufacturer’s values are the reference. For maintenance you can follow IEEE C37.10 or the NETA guidelines. IEC 62271-100 and IEEE C37.09 are product standards for type and routine tests.

Factory Acceptance Test (FAT)

At switchgear manufacturers assembling switchboards. The analyser is the standardised measurement basis with which the manufacturer demonstrates that the delivered product is within spec. Reporting matters here: digital export to PDF/Excel via the included DMP software, integrable in the FAT report for the end customer.

Both models are functionally identical in analysis capabilities — the same 7-inch touchscreen, the same timing accuracy of 0.05% rdg ± 0.1 ms, the same motion analysis, built-in printer and IP67 case. They differ in the number of contact channels (3 versus 6) and in the optional case. The number of channels determines which work you can carry out efficiently.

Each channel detects both the main contact and the insertion resistor contact. With 3 contact channels you have one channel per pole. On a three-phase breaker with one interrupter per pole you therefore measure all three phases in one run and read the synchronicity directly. You need the 6 channels of the CIBRE-60 for breakers with two interrupters per pole, or when you want to measure two breakers at the same time.

Rule of thumb:

• Does your breaker have one interrupter per pole? Then the CIBRE-30 is enough, also for all three phases at once.
• Working on breakers with two interrupters per pole, or want to measure two breakers at the same time? Choose the CIBRE-60.
• Unsure, or do you come across both types? Then take the CIBRE-60, so you can also measure breakers with two interrupters per pole in one run.

The table below shows the most relevant differences — and the similarities — between the CIBRE-30 and CIBRE-60. For the full list, see the product pages.

Both models are available in four variants: the base version and three versions with a suffix. Which one you choose depends on your field work:

• BLUE — Bluetooth module for wireless data transfer to laptop or tablet.
• B — built-in Li-ion battery for off-grid field work.
• B BLUE — both options combined; the most practical configuration for mobile field service.

Additionally, you choose per project which encoder fits the mechanism: a 325 mm linear encoder for straight-line contact movements, or a rotary encoder for rotating mechanisms such as in certain MV vacuum breakers.

Unsure between models or variants? Walk through these four questions and the choice almost always becomes clear.

1. How many interrupters per pole?

One interrupter per pole → the CIBRE-30 suffices, also when you measure all three phases at once. Two interrupters per pole, or two breakers at the same time → CIBRE-60.

2. Do you need motion analysis?

Yes → stay with the CIBRE-30 or CIBRE-60. No, only contact timing is enough → look at the lighter CIBRE-L3 or CIBRE-L6 (timer series, 3 kg, lower priced).

3. Do you often work outdoors or without mains power?

Yes → choose the B variant with built-in Li-ion battery. Always working at locations with mains power → the base configuration suffices.

4. Do you want wireless data transfer?

Yes → choose the BLUE variant with Bluetooth. For the most flexible configuration: B BLUE (battery + Bluetooth).

An analyser rarely stands alone. For a complete breaker diagnosis you combine it with additional measurements:

• Contact resistance in micro-ohm range — for example with an ARES-200D — to measure the contact resistance of the main contacts. Important for detecting contamination or erosion of vacuum bottles or contact surfaces.
• Substation commissioning on large-scale projects — for which we provide the SUWI-120 (rental), which combines contact timing with relay timing, turns ratio, contact resistance up to 120 A DC and tests on miniature circuit breakers (MCB).
• Periodic calibration of the measuring equipment itself — IONIO recommends a 12-month interval for the CIBRE analyser to remain within spec. You receive an automatic reminder 6 weeks before expiry via our ERP system. ISO17025 calibration available on request.

The included DMP software from HighTest handles reporting toward end customer and archive. Combine it with your ERP or CMMS system for traceability of measurements per breaker across the lifecycle.

A good measurement stands or falls with the operator. IONIO provides on-site installation, hardware and software configuration, and operator training on the CIBRE analyser. For more complex test routines with motion analysis, V1/V2 voltage signals, and coil current logging we recommend at least a half-day training. That pays back in more reliable measurement results and shorter throughput time on site.

Which configuration fits you depends on your breaker types, test volume and reporting requirements. Call or email our technical office; we’ll put together a quote — purchase, rental or an on-site demo.

Related: circuit-breaker contact timing test.