Archivo de pruebas

1. Make out most of your timing tests
Abstract
The timing tests are made to determine the time required for circuit-breakers or components to
operate on open, close, close-open and reclosing operations. However, everybody is aware that on
circuit-breakers, those are the typically used test sequences. But what do they really mean? How do
they refer to the standards?
Introduction
A circuit-breaker is a mechanical switching device, capable of making, carrying, and breaking currents
under normal circuit conditions, also making and carrying for a specified time, and breaking currents
under specified abnormal circuit conditions such as those of short-circuit. Therefore this constitutes
an important and critical component in the electric power system. During commissioning and
maintenance of circuit-breakers, one of the most common offline test methods have been the timing
tests, among others; a brief explanation of these tests is: measure the mechanical operation time
when the circuit-breaker is performing a mechanical sequence under no-load condition. So, this paper
presents the explanation of the standards for each test sequence and then, the application and how
to interpret the results of the timing tests.
Timing tests and Standards
The standards IEC 62271-100 and ANSI C37.100-1992 both contain explanations of sequences and
operations defined for circuit-breakers. In fact, the sequences defined are close (C), open (O), close-
open (CO) and open-close (O-C); and then the rated operating sequences or duty cycles.
Firstly, timing tests are done in the factory during the routine tests, then typically during the
commissioning tests. In addition to timing tests, during the routine tests is also measured time spread
between units of one pole and between poles, recharging time of the operating mechanism device,
consumption of the tripping and closing devices and possible recording of the current of the releases,
duration of opening and closing command impulses, ohmic resistance of the main circuit and time-
travel chart, among others. The assessment of these tests, during the commissioning or maintenance
is done comparing the results obtained with the results obtained in the routine tests.
Opening time
The opening time is measured during an operation by which the device is brought from the closed
position to the open position. The letter O signifies this operation. According to the standards
mentioned above, the opening time is the interval of time between the instant of energizing the
opening release, the circuit-breaker being in the closed position, and the instant when the arcing
contacts have separated in all the poles. If the circuit-breaker has more than one interrupting unit per
pole, the instant when the arcing contacts have separated in all poles is determined as the instant of
contact separation in the first unit of the last pole. Figure No. 1 illustrates the opening operation
according to IEC 62271-100.

2. Figure No. 1 Opening operation
However, on site, while the commissioning, maintenance and during no-load operation, when the
opening timing test is performed, just is possible to measure the opening time, such as seen in the
Figure No. 1a. The arcing and break times are not possible to measure because there is no way to
measure the arc duration and extinction when the circuit breaker is performing a no-load operation.
Figure No. 1a Opening timing test

3. Closing time
The closing time is measured during an operation by which the device is brought from the open
position to the closed position. The letter C signifies this operation. The closing time is the interval of
time between energizing the closing circuit, the circuit-breaker being in the open position, and the
instant when the contacts touch in all poles. This closing time includes the operating time of any
auxiliary equipment necessary to close the circuit-breaker and forming an integral part of the circuit-
breaker. The Figure No. 2 illustrates the closing operation according to IEC 62271-100.
Figure No. 2 Closing operation
So, for the same reasons that the arcing time cannot be measured as was explained in the opening
operation, also the pre-arcing time cannot be measured. While commissioning, maintenance and
during no-load operation when the closing test is performed, just is possible to measure the closing
time. Just as shown in figure 2a.

4. Figure No. 2a Closing timing test
Simultaneity or synchronization
When timing tests are performed, is essential to analyze the synchronization time between poles and
interrupting units per pole, as long as there more than one interrupting unit per pole. In fact, according
to IEC 62271-100 and ANSI C37.04-1999, when no special requirement with respect to simultaneous
operation of poles is stated, the maximum difference during opening shall not exceed 1/6 of a cycle
of rate frequency and during the closing shall not exceed 1/4 of a cycle of rate frequency as well.
Figure No. 3a Synchronization time closing operation Figure No. 3b Synchronization time opening operation
If one pole consists of more than one interrupter unit connected in series, the maximum difference
between the instants of contact separation within these series connected interrupter units shall not
exceed 1/8 of a cycle of rated frequency, and between the instants of contacts touching within these
series connected interrupter units shall not exceed a 1/6 of a cycle of rated frequency. Sometimes,
the simultaneity of poles also is called time spread between poles or between units of one pole. In the
figure 3c are showed the synchronization times.

5. Figure No. 3c Synchronization times
Close-open time
The close-open time is measured during an operation by which the device is brought from the open
position to the closed position followed immediately by an open operation without purposely delayed
action. The letters CO signify this operation. The close-open time is the interval of time between the
instant when the contacts touch in the first pole during a closing operation and the instant when the
arcing contacts have separated in all poles during the subsequent opening operation. The Figure No.
4 illustrates the closing operation described by the standard IEC 62271-100.
Figure No. 4 Close-open operation
This sequence also is known with the name of short-circuit time or trip-free operation. With this
sequence also is possible to perform the simulation of fault-making operation, or in other words, a
tripping operation after the circuit-breaker has been closed under a fault condition.
Since that only one closing operation of the circuit-breaker mechanism shall result from each close
command, even though the circuit-breaker trips while the close command is still applied and

6. maintained. This requirement ensures that the circuit-breaker will not pump if it trips during a closing
operation. It means that, with this sequence, is also possible to test the anti-pumping function. In the
figure 4a is showed the close-open timing test.
Figure No. 4a Close-open timing test
Open-close time
This sequence is known with the name of reclosing cycle or auto-reclosing operation. The open-close
time is measured during an operation by which the device is brought from the closed position to the
open position, followed immediately by a close operation. The letters O-C signify this operation. The
open-close time during auto-reclosing is the interval of time between the instant when the arcing
contacts have separated in all poles and the instant when the contacts touch in the first pole during a
reclosing cycle. Also, the reclosing time is defined as the interval of time between the beginning of the
opening time and the instant when the contacts touch in all poles during a reclosing cycle. The Figure
No. 5 illustrates the open-close operation described by the standard IEC 62271-100.
Figure No. 5 Open-close operation

7. With this sequence, a closing operation after the circuit breaker has tripped to clear a fault is
simulated. In the figure 5a is showed the open-close timing test.
Figure No. 5a Open-close operation
The rated operating duty cycle, as is referred in ANSI, is known as the rated operated sequence by IEC.
Normally there is some confusion between the standard duty cycle and reclosing duty cycle, the
standard duty cycle is the basis of circuit breaker design, application and design testing. The standard
duty cycle establishes a uniform basis for the performance of the circuit breakers. Also, it establishes
a uniform basis for the short-circuit design tests conducted in the power laboratory. And by the other
hand, the reclosing duty cycle is just used in a particular application, for example an auto-reclosing in
a radial transmission line. For rated operating duty cycle ANSI specifies the standard operating duty
as a sequence consisting of the following operations; O – 15 sec – CO – 3min – CO, that is an opening
operation followed, after a 15 second delay, by a close-open operation and finally after a 3 minute
delay by another close-open operation. For circuit breakers intended for rapid reclosing duty the
sequence is O – 0.3sec – CO – 3min – CO.
IEC offers two alternatives, one is O – 3min – CO – 3min – CO and the second alternative is the same
duty cycle prescribed by ANSI. However, for circuit breaker that are rated for rapid reclosing duties
the time between the opening and close is reduced to 0.3 seconds. In fact, ANSI establishes that the
minimum reclosing time of a circuit breaker is 0.3 seconds. This is the shortest permissible time in
which the circuit breaker is required to close.
Figure No. 5b illustrates the rapid reclosing duty sequence O – 0.3s – CO.
Figure No. 5 rapid reclosing duty sequence

8. References
[1] Garzon, Ruben: High Voltage Circuit Breakers Design and Applications. 2nd Ed. 2007; New York,
Marcel Dekker
[2] ANSI C37.04-1999 Standard
[3] ANSI C37.100-1992 (R 2001) Standard
[4] IEC 62271-1 :2007 Standard
[5] IEC 62271-100 :2007 Standard