Siemens siprotec 7SD5 User Manual

3.3 Commissioning
507
7SD5 Manual
C53000-G1176-C169-1
3.3.10 Measuring the Operating Time of the Circuit Breaker
Only for Synchro-
nism Check
If the device is equipped with the function for synchronism and voltage check and it is
applied, it is necessary - under asynchronous system conditions - that the operating
time of the circuit breaker is measured and set correctly when closing. If the synchro-
nism check function is not used or only for closing under synchronous system condi-
tions, this section is irrelevant.
For measuring the operating time a setup as shown in Figure 3-34 is recommended.
The timer is set to a range of 1 s and a graduation of 1 ms.
The circuit breaker is closed manually. At the same time the timer is started. After
closing the poles of the circuit breaker, the voltage U
Line
appears and the timer is
stopped. The time displayed by the timer is the real circuit breaker closing time.
If the timer is not stopped due to an unfavourable closing moment, the attempt will be
repeated.
It is particularly favourable to calculate the mean value from several (3 to 5) successful
switching attempts.
Set the calculated time under address 239 as T-CB close (under P.System Data
1). Select the next lower settable value.
Note
The operating time of the accelerated output relays for command tripping is taken into
consideration by the device itself. The tripping command is to be allocated to a such
relay. If this is not the case, then add 3 ms to the measured circuit breaker operating
time for achieving a greater responce time of the „normal“ output relay. If high-speed
relays are used, on the other hand, you must deduct 4 ms from the measured circuit
breaker operating time.
Figure 3-34 Measuring the circuit breaker closing time
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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English