The FRANEO 800 is OMICRON's instrument for sweep frequency response analysis (SFRA) of power transformers and the successor to the FRAnalyzer. It injects a low-voltage sine signal from 1 Hz to 30 MHz at one end of the winding and compares the response with a reference fingerprint to detect deformation, displacement and core problems without opening the tank.
What it is and where it is used
The FRANEO 800 is an OMICRON instrument for sweep frequency response analysis (SFRA) of power transformers. According to the manufacturer, it is the successor to the FRAnalyzer, the instrument that made OMICRON well known for this test. It is used in substations and industrial plants with medium-, high- and extra-high-voltage transformers, and also on reactors, to check the mechanical condition of the core and windings without opening the tank. This is complemented by transformer turns ratio out of tolerance.
What the test is, when it is done and how it is interpreted is covered in the guide on frequency response analysis (FRA). This page is about the instrument: what it is, what it is for and what it includes.
The FRANEO 800 measures in the frequency domain. It applies a low-amplitude sine voltage of increasing frequency at one end of a winding and measures the signal that arrives at the other end. Because the transformer behaves as a network of capacitances, inductances and resistances, each unit has its own response, its «fingerprint». If the winding moves or deforms, the fingerprint changes.
Variants: FRAnalyzer and FRANEO 800
| Model | Application | Main difference |
|---|---|---|
| FRAnalyzer | Transformer SFRA, previous-generation instrument | OMICRON presents it as the instrument that the FRANEO 800 succeeds |
| FRANEO 800, Standard Package (VE000661) | SFRA with clamps and aluminum braids for the bushings | Instrument, bushing and flange clamps, ground braids and Primary Test Manager software |
| FRANEO 800, Quick Connection Package (VE000662) | SFRA with faster connection | Integrated cables with the ground reference in a ring and easy-connect clamps, plus the same software |
Accessories are also offered, such as a set of clamps for short bushings and an upgrade option to the quick connection.
Main features
The data below are the ones OMICRON declares in its FRANEO 800 brochure (May 2019); confirm the current values with the manufacturer’s up-to-date data sheet before planning a job.
| Item | Declared value |
|---|---|
| Frequency range | 1 Hz to 30 MHz |
| Dynamic range (20 Hz to 2 MHz) | Greater than 150 dB |
| Typical accuracy | ±0.1 dB down to −50 dB and ±0.3 dB between −50 and −100 dB |
| Output voltage | 0.1 Vpp to 10 Vpp into 50 Ω, adjustable |
| Connection | BNC, double-shielded coaxial cables |
| Weight and size | 1.8 kg; 252 × 53 × 265 mm |
| Power supply | Built-in battery, useful where there is no mains supply |
It also has functions designed for reproducibility, which decides whether a comparison is worth anything:
- Bushing clamps with tips that cut through paint or dirt and give a stable contact.
- Flat ground braids of low inductance and flexible length, which must lie against the bushing; the manufacturer bases its high-frequency repeatability on them.
- Ground loop check, which gives a pass or fail result and can block the measurement if the braids are not properly connected.
- Smart sweep, which first runs through the whole band and then concentrates on the critical zones to shorten the time.
What SFRA detects with this instrument
The manufacturer lists as detectable defects the axial and radial deformation of windings, displacement between the high- and low-voltage windings, and partial winding collapse. Also shorted or open turns, faulty grounding of the core or the shields, and core movement. The list is completed by broken clamping structures and problematic internal connections. These are mechanical changes and changes in the magnetic circuit. SFRA does not measure insulation degradation: for that there are power factor and tan delta, dielectric frequency response and oil analysis.
An SFRA result outside what is expected does not explain the cause by itself. It usually leads to complementary tests, such as leakage reactance, excitation current or winding resistance, before deciding whether the transformer stays in service. On leakage reactance, see the short-circuit impedance test (Z).
Software and integration
The FRANEO 800 is operated with Primary Test Manager (PTM), OMICRON’s software for transformer testing. According to the brochure, PTM:
- manages locations, assets, jobs and reports in a database;
- offers test templates and connection diagrams according to the vector group;
- automatically selects the reference measurement of the same transformer and compares it with a mathematical method based on the Chinese standard DL/T 911-2004;
- exports data and reports in XML, PDF, Word and Excel, and synchronizes databases with a server through an optional module;
- is complemented by the PTMate mobile app, which lets you start and stop measurements from the phone.
The instrument connects to the computer by USB. OMICRON states that operating the FRANEO 800 with PTM makes it possible to meet IEC 60076-18 and IEEE C57.149, and that its connection technique is based on method 1 of IEC 60076-18.
Precautions and mistakes that ruin a comparison
SFRA is a comparative method, so almost all problems come from two measurements not being comparable with each other:
- Different connection. Changing the contact point on the bushing, the length or routing of the ground braid or the side that receives the signal moves the curve, especially above a few hundred kilohertz. That is why the configuration is documented with the fingerprint.
- Transformer state. The tap changer position, remanent magnetism (for example after measuring winding resistance with direct current) and whether the oil is in the tank or not change the low-frequency response. It is best to always measure under the same conditions.
- No reference. If there is no fingerprint of the same transformer, it is compared with a twin unit or between phases; this is less conclusive and demands more judgment.
- Reading only the numerical index. An acceptable correlation coefficient does not rule out a local change in a narrow band; the reading is done by frequency zones, which the manufacturer associates with core, windings and connections.
Frequently asked technical questions
- FRAnalyzer or FRANEO 800: the FRANEO 800 is the instrument that OMICRON presents as the successor. Historical measurements made with the FRAnalyzer remain useful as a reference fingerprint, and the software can import them.
- Manual and software: the manual and PTM updates are provided by OMICRON to its customers; this page is limited to what the manufacturer declares in its public brochure.
- When to repeat the test: the reference fingerprint is taken as early as possible in the life of the transformer (factory or commissioning) and repeated after events such as a nearby short circuit, transport or an earthquake.
- Reference standard: IEC 60076-18 defines the SFRA measurement; the application and interpretation guide is IEEE C57.149, whose current edition is 2024 (the brochure cites the 2012 one).
How we help
Do you need this test? We do it for you: depending on your case we recommend the right test and instrument and include it in the quotation. That way you get the test your case really needs, without paying for extra tests.
See the scope in power transformer testing and in testing and commissioning, done in Colombia or elsewhere on request, or tell us about your case through the contact page.
Related guides
- Frequency response analysis (FRA): what it detects
- Dielectric frequency response test
- Power factor and tan delta test
- Short-circuit impedance (Z) test on power transformers
- Commissioning of power transformers
- Transformer core and windings
- Transformer Turns Ratio Out of Tolerance: Causes
References
- IEC 60076-18, Power transformers – Part 18: Measurement of frequency response.
- IEEE Std C57.149, guide for the application and interpretation of frequency response analysis for transformers (2024 edition current).
- OMICRON, brochure «FRANEO 800: The next generation for a reliable core and winding diagnosis of power transformers», May 2019 (English).
- CIGRE Technical Brochure 342 (2008), Mechanical condition assessment of transformer windings using Frequency Response Analysis (FRA).
Frequently asked questions
What is the difference between the FRAnalyzer and the FRANEO 800?
OMICRON presents the FRANEO 800 as the successor to the FRAnalyzer. Both apply the SFRA principle. The FRANEO 800 brings a connection technique with bushing clamps and ground braids, a built-in battery and the Primary Test Manager software. According to the manufacturer, measurements saved with the FRAnalyzer database can be imported into the new software with a migration wizard.
Can a measurement made with the FRANEO 800 be compared with one made with another SFRA instrument?
Within certain limits, yes. The FRANEO 800 lets you set the output voltage between 0.1 Vpp and 10 Vpp precisely so that you can compare with earlier measurements made with other instruments. The comparison still requires the same connection and grounding configuration, because the method is comparative.
Does SFRA give a pass or fail result?
Not automatically. The method compares the current response with a fingerprint of the same transformer (or with that of a twin unit or another phase), and a specialist does the interpretation, cross-checking the result with other tests. The software calculates comparison indicators, but it does not replace that judgment.