HV TECHNOLOGIES, Inc.

Many dielectric and mechanical failures in large power transformers are preceded by mechanical changes in the winding structure. The FRA 5311 Sweep Frequency Response Analyzer detects transformer winding movements and mechanical failures due to mechanical shock, transportation or short circuits. Detection of these displacements ahead of a dielectric failure can reduce unplanned maintenance costs, and provide the possibility to improve system reliability by preventing outages. Additionally, when damage is discovered, repairs may be targeted to a specific phase winding. Changes in the winding geometry will be reflected by deviations between repeated measurements. Even small winding movements or distortions will cause legible changes in the measured transfer function, which is clearly detectable.

The FRA 5311, the smallest and lightest device in the industry, is extremely easy to use. Just plug it to a USB port in the computer (for communications and power), start the windows based software and perform the test. The clever grounding connection guarantees measurement repeatability even up to high measuring frequencies. The additional analysis mode allows easy comparison between curves. In addition measurements from other FRA manufacturers can be loaded by using the IEC 60076 recommended XML format, or by importing them directly (most common FRA manufacturers available).

The 2293 is an automatic winding resistance analyzer, optimized for three phase power and distribution transformer measurements. It uniquely combines winding resistance measurement, turns ratio measurement, core demagnetization, transformer type detection, magnetic balance and heat run test (temperature rise and cooling curve) in the fastest single instrument solution on the market.

A simple “one-time-connection” system drastically reduces measuring time: once connected all tests can be performed in a row without any reconnection. The built-in simultaneous winding magnetization method guarantees fast and reliable resistance measurements. Stable measurements are reached even on large power transformers with delta windings on the low voltage side. A progressive method for measuring transformer turns ratio guarantees results closer to the nominal ratio even in large power transformers with tertiary windings.

The demagnetization function eliminates the magnetic remanence, which can cause faulty measurements, high inrush currents and incorrect operation of protective relays.

The DDX 9160 is a lightweight and portable PD detector from Haefely for AC, DC, and RIV partial discharge measurements. The fully digital state-of-the-art detector can accommodate up to four simultaneous PD/RIV and Voltage inputs. The modular design fits a wide range of PD detection applications. Conventional AC & DC PD measurements according to IEC 60270 or RIV measurements according to NEMA and CISPR standards are covered. The DDX 9160 can be operated by battery or by using an external power supply. Together with the optional integrated measuring impedance, the DDX 9160 is ideal for on-site PD measurements when an existing coupling capacitor is available or for power transformer PD measurements using the bushing tap method.

Haefely’s CaMS software platform provides the most modern, flexible, and user-configurable PD application software on the market. The software enables the controlling of single channel, multi-channel (up to 4 channels per unit) and/or multi-detectors (up to 3 units connected in a daisy chain). A dark mode display includes all the required PD analysis tools such as meters, pulse diagram, PRPD pattern (fingerprinting), data logger and more. The number of meter indicators, as well as their size, can be selected. Reports can be easily created in pdf format.

Fiberoptic cables provide galvanic isolation, ensuring the full safety of the operating personnel. Measurement sensitivity is increased with the most flexible digital filters available on the market allowing the frequency measurement band to be shifted into a less noisy range and suppressing frequency-dependent noise.