cba example application 2012

7/29/2019 CBA Example Application 2012

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EXAMPLES OFAPPLICATIONS FOR THECBA-32P


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What is a Circuit Breaker?

A circuit breaker is an automatically operated electrical switch

designed to protect an electrical circuit from damage caused by

an overload or a short circuit.

Unlike a fuse, which operates once and then has to be replaced,

a circuit breaker can be reset (either manually or automatically)

to resume normal operation. Essentially, a circuit breaker is a

safety device.


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What is a Circuit Breaker Analyzer?

A Circuit Breaker Analyzer (CBA) is an electrical test

equipment designed to perform timing and other tests such

motion analysis on any circuit breaker.

A wide range of tests have been developed to verify the

conformity of each of the electrical and mechanical properties

of a circuit breaker in order to meet the design criteria.

Some of these tests are acknowledged and documented by

international standards (IEM, ASTM, etc.). Some are still underdevelopment and promise great expectations.


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What is a Circuit Breaker Analyzer?

CBA-32P is mainly designed to perform timing and motionanalysis but it is also an excellent multifunctional oscilloscopethanks to its compatibility with several accessories.

By means of the accessories, the following measurement tests

can be performed:- breaker travel and velocity

- main and arcing contact resistance curve

- voltage, current, pressure, temperature, etc.

- insertion resistance during the opening and closinga times of the breakers auxiliary contacts

The tests are executed under the control of CbaWin, runningunder any Windows.
http://www.zensol.com/brochure/MULTIFUNCTIONAL_CBA.pdfhttp://www.zensol.com/brochure/MULTIFUNCTIONAL_CBA.pdf


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How to get started? In order to execute the test, the circuit breaker has to be set off line.

The CBA-32P is connected via cables to both the computer and the breaker :

To the computer via optical fiber communication module

to the contacts of the circuit breaker via contact cables

to the control cabinet (open and close coils) via the command cables

Command-signals are sent from the CBA-32P to the control cabinet and the contacttiming is measured through the cables.

The contacts may have up to three possible states visualized in the CbaWin software:

Open (0)Resistive (0.5)Close (1)

All recorded data are automatically and instantaneously transferred to the CbaWinsoftware which analyses the data and displays the results of the tests in graphics andtabular formats.


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EXAMPLE 1 : Timing Tests -Inoperative resistor

The insertion resistor does not work.

The spring on the moving contact is

broken and blocks the piston.

The broken spring has been replacedwith a new one and the device hasbeen reassembled.


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EXAMPLE 1 : Timing TestsRebounds

Abnormal rebound on an auxiliary

(resistive) contact. The head on the

semi-mobile contact is loose.

The auxiliary moving contact has beendisassembled and the problem has been identifiedas a loose head. The head has been tightened andimmobilized with loctite and punching, followedby reassembly of the mechanism.


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EXAMPLE 1 : Timing TestsDead Tank Missing Main contact

Case of an inoperative main contact onone phase (B), showing an open circuiton a close operation.

Disassembling the defective parts its been

possible to observe that a shaft, connecting the

actuating rod to the moving contact, had fallen

causing the contact piston to separate from the

actuating rod. The shaft has been replaced.


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EXAMPLE 1 : Timing TestsDead Tank Bad damping

This timing diagram suggests a lack ofdamping at the end of the travel.

The damage was due to a defectivedashpot.


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EXAMPLE 1 : Timing TestsValve in wrong position

The body of the valve has been installedat 90 with respect to its normal position,hence causing delays in the admission ofcompressed air. The closing time ofcontacts A-1 and A-2 results longer thanusual, as observed on their signals.

The body of the valve has beendisplayed in the correct configuration.The closing time of contacts A-1 andA-2 now corresponds to the one of A-3 and A-4, as observed in the newgraphic.


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EXAMPLE 1 : Timing Tests Adjustmentscrew of hydraulic command incorrectly set

An adjustment screw is incorrectlyset, creating a 25 ms difference onone phase.

The problem has been solved afteradjusting the screw.


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EXAMPLES 1 : Timing Tests Hydraulicactuator - Short circuit time

The admission restriction of thehydraulic actuator is such that the shortcircuit time on phase C is longer than theother phases.

The admission restriction of thehydraulic command has been adjustedin order to obtain synchronousoperation for all the phases.


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EXAMPLE 1 : Timing TestsPneumatic Breaker Isolation time

Phase C is much quicker than the twoother phases.

The restriction on the inverter switchhas been adjusted in order to obtaincomparable times between phases.


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EXAMPLE 1 : Timing Tests ShieldedBreaker

The travel course is not completed, (112mm instead

of 180mm). The piston starts moving 30 to 35

milliseconds after the main piston while the normal

delay is 20 milliseconds.

The problem is solved by increasing the appropriatediaphragm orifice by 0.020 inches. The prematurereopening of the resistor was due to the main contactclosing later. Besides, the curve shows a problem withthe upper piston (DpC) of the main contact on Phase C.This piston was overhauled prior to the timing test.


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EXAMPLE 2 : Time-travel tests on HVcircuit breaker

The circuit breaker tested in this example is a PK8D - ALSTOM

(800KV - 24 contact breaker)

The steps to execute the test are the following:

-1. Preparation of the breaker

-2. Installation of cables by human operators

-3. Connection of CBA-32P

-4. Execution of the test with test plans-5. Presentation and discussion of the results

-6. Conclusions


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1. Preparation of the breaker: securing the site

The first step consists in the isolation of the breaker from the electricnetwork by means of disconnectors, which are displayed on each side of the

circuit. After isolation, the breakers are closed in order to ground the entire circuit.

In order to guarantee the maximum safety for the operators, it is highlyrecommendable to put the ground on each side of the breakers.


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Detail of disconnectors:

They isolate the circuit

from the line.

High voltagebreaker

Current

transformers


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2. Installation of the cables

Operators proceed to the

installation of the cables

on the breaker

The installation is

typically performed with

the help of a bridge


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Yellow cable Red cable

Black cable

To the inputs of the CBA-32PExtensions for the connection of

the CBA-32PContact cables


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3. Cables for the CBA-32P:

Command

cable

Extensions cables

Contacts cable


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Overview of the CBA-32P connection and components:

Portablecomputer

24 contact CBA-

32P

Grounding of

the CBA-32P

Command

6 analog inputs

Optical fibre link


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Optical fibre connection:

The optical fibre cable

puts in communication the

CBA-32P and the

computer


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Connection of the command cables:

The green cable commands the

opening of the breaker

Control cabinet

The red cable commands the closing

of the breaker


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EXAMPLE: Time-travel tests on HVcircuit breaker

Connection of the CBA-32P:

The command cable mustbe connected here

Contacts cablesOptical fibre

Command cable


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Execution of the test: loading a test plan


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EXAMPLE2 : Time-travel tests on HVcircuit breaker

Execution of the test: creation of a test link

Test link


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Test of the optical fibre link:


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Execution of a cable test:

Contact cable test


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Execution of a test for the cables connected to the breakers:


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Launching a test:

Launch the test


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5. Presentation and discussion of the results:

Bad fixation of the cables (the

black clip is probably

disconnected)

The black clip falls during theclosing of the main contacts


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Closing test on a 24 contacts


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Opening test


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Close-Open test


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Problem on the A phaseContacts A01-A02 : We notice the

apparition of the insertion resistance on

the close side that could derive from a too

long safety time. The contact traces of

resistances have to be separated. In thisway, it will be possible to see the

complete resistance traces. If necessary,

the safety time can be readjusted. This

operation will require the dismantlement

of the resistances cables, and hence, to

work on the timing diaphragms.

In this case, the problem could be also

solved by increasing the timing. This is

possible since the opening time of this

contacts is quicker than the others on the

same phase.


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Open-Close-Open test


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Problems on phase B

The isolation time of phase B is too

long: the timing of the pneumatic

inverter switch (52bb) is too long. Inorder to work on the timing, the

breaker has to be dismantled.

Note: A good way to test the 52bb

on the three phases is to perform an

O-C test with a delay of 20 ms

between the O and the C. Thismeans that the breaker has to be in a

close status till the end of the test.


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The results of any test can be visualized in Tabular report,

as follows:

cba example application 2012

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