Chapter 1 - 7SR45 Description of Operation
©2018 Siemens Protection Devices Limited Chapter 1 Page 43 of 48
3.16.2.2 Time Delayed Overcurrent Protection during Start up (51, 51G, 51N)
The operating time of the protection functions (51, 51G, 51N) are optimized at the lower current settings when the
relay is energized with the short-circuit current or fault current.
The optimization of the operating time is done only in the start up condition for the first 25 AC cycles if the fault
current persists.
The optimization is done as per the sensitivity characteristics of the binary output. However, the operating time of
the pulse output also improves if the calculated operating time is less than the pulse output sensitivity
characteristics.
NOTE:
The following conditions must be considered for the optimization algorithm:
1. If the calculated operating time is less than the boot up time as shown in the sensitivity graph (
Figure 3-14
,
Figure 3-16
), then the optimization is not effective.
2. If the battery is low, the calculated boot up time is increased, the optimization is not effective.
3. When the device is started with the load current and the fault current appears within 25 AC cycles, then the
operating time will be less than the calculated time.
4. It is recommended to keep the
Time Multiplier
setting to more than
0.1
.
5. The optimization of the operating time is not effective if the fault current is not stable during the boot up time.
3.16.3 USB
In the USB mode, all the settings can be edited even if the protection functions are inactive. The binary inputs and
binary outputs are operational in the USB mode. In the USB mode, the local flag indicator reset is only possible.
The pulse output and remote flag output cannot be operated with USB.
3.16.4 Battery
In the battery mode, the relay can be energized by pressing the
BAT ON/OFF
key or if any binary input status is
changed.
The battery is used to operate 7SR45 Argus Relay only when other power sources are not available.
In the battery mode, all the settings can be edited even if the protection functions are inactive. The binary inputs
and binary outputs are operational in the battery mode. In the battery mode, the local flag indicator reset is only
possible. The pulse output and remote flag output cannot be operated with battery.
In the battery mode, if no keys are pressed for 60 s, the relay goes to sleep mode automatically.
By default, in the battery mode, the backlight is OFF and it can be TURNED ON by pressing the backlight key.
3.16.4.1 Battery Profile
The Battery Profile menu provides the consumption on battery power of the different application modules.
The table 3-15 shows the battery profile parameter data and the status of the operations performed on the battery
power.
Table 3-15
Battery Profile Parameter
Battery Profile Parameter Description
Unit
Device ON Dur’n
The duration of the device powered on with the battery source only.
Seconds
Backlit ON Dur’n
The duration of the LCD backlight powered on with the battery source
only.
Seconds
BO Oper’n Count
The number of times the binary outputs operate with the battery
source only.
-
BI Oper’n Count
The number of times the binary inputs operate with the battery source
only.
-
The battery profile parameters data can be cleared with the DATA STORAGE >
Clr Battery Data
setting in HMI.
NOTE:
When replacing the new battery, the battery profile parameters data must be cleared.