Siemens 7SA511 manual Synchronizing the Clock, Parameter Changeover Optional

7SA511 Line Protection Relay Programming the Relay

difference time, press the +/-key, then press the Enterkey. The format for entering the difference time is the same as for a new time as described above.

Synchronizing the Clock

There are two ways to precisely synchronize the relay clock with another reference:

1.via the operator panel

2.via a binary input signal

Operator Panel Entry

Synchronizing the clock through the operator panel can be done with either a set time entry or a difference time entry.

To synchronize with a set time entry, use address 8103 and enter a time in advance of the reference time, then press the Enterkey precisely when the reference clock reaches the entered time. This method can never be extremely precise since it is dependent on operator reaction time.

To synchronize with a difference time entry, use address 8104 and enter a time equal to the time difference between the relay clock and the reference clock. The difference time method has the advantage of being independent of the operator reaction time. It does, however, have the disadvantage of having to know the exact time difference between the relay clock and the reference clock.

Binary Input Signal

The relay clock may also be synchronized by means of an external signal on a binary input. In order to use this method, the logical function “Time Synchro” (FNo 005) must be assigned to a binary input (see section 5.19.3). When “Time Synchro” is assigned to a binary input, a transition of the input signal to the active state causes the seconds counter of the internal clock to reset to zero. The minutes counter will advance to the next minute if the seconds counter is at 30 seconds or more when the transition occurs. Otherwise, the minutes counter will remain unchanged. Worst case delay between the synchronizing transition and the reset to zero seconds is 20 milliseconds.

The internal clock accuracy allows a maximum deviation of 8.64 seconds per 24 hour period. It is, therefore, recommended that elapse time between synchronizing signals not exceed 3 days (72 hours).

5.8 Parameter Changeover (Optional)

Another optional feature of the 7SA511 relay is the ability to program multiple parameter sets and to change the operating parameter set when desired. This feature, called parameter changeover (PCO), provides four parameter sets—identified by the letters A, B, C, and D—in addition to the original, default set. If your relay model number is 7SA511*-**A5*-**E/F/G*, your relay has the parameter changeover feature. Skip the rest of this section if your relay does not have this feature.

System settings and relay protection settings (addresses 1000 to 3999) can be uniquely defined for each parameter set. You can also copy data from one parameter set to another, including the original set.

5-18 July 27, 1995