PKV/U3: versatile instrument. Objective evaluation of the state of high-voltage circuit breakers

9 december 2019

Most instruments for monitoring high-voltage circuit breakers available on the market today do not provide objective information about the technical condition of circuit breakers, because they do not take into account the features of checking either new or outdated equipment. Thus, the lack of objective information about the technical condition of the equipment leads to losses and waste of funds for its maintenance and repair.

Today, in the Russian market for monitoring high-voltage circuit breakers, there is a whole group of devices that differ from each other in the number of simultaneously controlled breaks, ways to adapt to various circuit breakers, temperature range, power supply voltage, the presence or absence of measurement methods, transducers used, additional functions, weight and, of course, price (see the table below).

WHAT YOU SHOULD BE GUIDED BY WHEN CHOOSING AN INSTRUMENT FOR EVALUATING THE STATE OF HIGH-VOLTAGE CIRCUIT BREAKER?

Question:

What parameters should be monitored for circuit breakers?

Answer:

Time characteristics, speed, and travel parameters. For air circuit breakers, the time characteristics must be controlled simultaneously via 18 channels (plus 10 channels of nozzle sensors), for SF6 circuit breakers – via 6 (12) channels, and for other breakers – via 3 channels.

As can be seen from the table below, the requirements for the number of discrete channels, channels of nozzle sensors and graphic information are met only by PKV/U3 which can be used for monitoring circuit breakers with a voltage of up to 1050 kV.

For air and SF6 breakers, the instrument can ensure:

obtaining the switching oscillograms and the automatically calculated parameter tables based on them;
speed measurement for SF6 circuit breakers using the transducers included in the breaker's scope of supply.

For oil circuit breakers:

installation of a linear and angular movements transducer to any oil circuit breaker;
automatic conversion of angular travel and speed values to linear values (for circuit breakers where only the angular rotation of the shaft can be controlled).

Unlike competitors, PKV/U3 can perform the mentioned measurements and calculations automatically.

Question:

What transducers are used to measure speed and travel?

Answer:

Digital transducers are more interference-resistant than potentiometric ones. This is inherent in the very principle of measurement. At substations of 500 kV and higher, potentiometric transducers are not able to operate under interference conditions.

Each type of circuit breaker imposes its own specific requirements on the composition of the instrument. Air circuit breakers require a large number of discrete channels, oil and SF6 breakers additionally require linear and angular movements transducers with attachment devices. In addition, the transducer must measure movements up to 900 mm, since many oil circuit breakers, namely dead tank ones, have such a large travel.

Instrument type	PKV/U3	TM-1800	SVA 1000
Air circuit breakers	+	+	+
SF6 circuit breakers	+	+	+
Oil circuit breakers	+	-	-
Vacuum circuit breakers	+	-	-
Discrete channels	20	16	16
Current measurement channels	up to 400A	up to 60A	up to 25A
Nozzle sensor channels	12	-	-
Transducer (L - linear, A - angular)	LA (digital)	LA (potentiometric)	LA (potentiometric)
Speed (V) and travel (S) charts	+	-	-
Maximum travel, mm	900	500	500
Operating temperature	-20 ÷ +45	-20 ÷ +50	-10 ÷ +50
Power supply voltage, V	~85-265, =100-375	~95-265	~85-265, =100-375
Measurement methods	+	-	-
Weight, kg	10	13	10.5

According to the table, a set of necessary digital transducers and attachment devices for circuit breakers is included in the complete set of PKV/U3, the linear movements transducer of this device can measure the travel up to 900 mm.

The accuracy of measurements depends on the correct installation of the transducer, so the device must include a method for conducting measurements on circuit breakers of any type.

Unlike competitors, PKV/U3 includes detailed measurement methods for all types of circuit breakers.

PKV/U3 is necessary not only for companies that operate circuit breakers, but also for organizations that are engaged in major repairs of old and installation of new equipment.