New approaches to monitoring of the technical condition of the outdoor switchgear equipment

Currently much attention is paid on issues of technical inspection of outdoor switchgear equipment (TT, TH, B, and so on) because the equipment is highly damageable.

Despite the widespread implementation of the normalized technical measures (ОНИЭ), the development and implementation of various diagnostic methods and significant costs of upgrade (replacement) of equipment, questions of assessing the reliability of outdoor switchgears are still open.

Obviously, the existing rules do not allow us to control an overall picture; the control conducted by specialized organizations periodically (every 1-2 years) does not allow tracking fast-growing insulation defects and, in essence, have zero effectiveness.

With extensive experience, as well as with sense of new and existing methods of control, it is necessary to develop a new concept of organizing technical condition monitoring of outdoor switchgears.

The basis of the new TSE methodology is the principle of synergies and incremental (step-by-step) control.

The first stage envisages the implementation of 100% control of the devices throughout the switchgear equipment using broadband radio frequency scanners (wide band & low-cost), to identify sources of electrical discharge activity (partial discharges, spark and arc processes, coronas, etc.).

Measurements are carried out by the operator of each machine, displayed and stored in the memory scanner. The data is then analyzed and a topological map of the intensity of discharge activity is compiled for all switchgear devices.

This technique has already been used previously for the diagnosis of ТФРМ transformers of voltage 330 -500 kV at FGC facilities. The advantages of this method are obvious - the speed control (all equipment is inspected under operating voltage), distance (lack of galvanic contacts with the circuits of control, operation, grounding, etc.), simplicity and clarity (no special skills required for diagnostics) and low cost (all the work can be performed by a single operator in the course of one shift). As a result, from the list of all (this is often hundreds of units) equipment there remains a reasonable small list of "problem" equipment that requires additional monitoring. A set of additional control procedures may be different, for each specific type of machine.

 In the second stage, the detection of defective unit(s) is followed with installation of a monitoring system with sensors and radio communications. The installation of these sensors (with up to 36) is carried out without shutting down the equipment, directly to conductor parts. At the heart of the system is the principle of acoustic partial discharge registration, that allows to avoid false alarms due to the communication and impulse noise.

For up to 3 months constant (or periodical by the choice of operator) control is held over the development of possible defects.

After that, system sensors can be removed (as well without switching off) or reinstalled on other equipment.

Thus, this is an opportunity to quickly identify faulty equipment with minimal costs and to conduct targeted monitoring of the technical state.

 The range of application of this approach is quite wide, already there are positive results of the implementation of these techniques for the control of power transformers, cable terminations of 110/220 kV (XLPE) and current transformers as the most critical devices for the distribution of electricity.