Siemens 7SR242 Duobias - 2.12 Overfluxing (24)

7SR242 Duobias Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 45 of 57
2.12 Overfluxing (24)
Figure 2-14 Under/Over Frequency
The settings are set in terms of V/f based on multiple of nominal voltage and frequency. Application of a voltage of
nominal voltage and frequency represents 1.0.
Testing is simplified by applying nominal frequency and increasing voltage only, such that the operating level is
simply the setting multiplied by Nominal Voltage.
2.12.1 definite time (24DT)
If DTL setting is small, gradually increase voltage until element operates.
If DTL is large apply 0.95x setting, check for no operation, apply 1.05x setting, check operation
Apply 0.9x voltage, increase to 1.1x setting and record operating time
Setting
(xVn)
Setting
(volts)
Hysteresis
(%)
Calculated
D.O.
(volts)
DTL
Setting
(sec)
P.U.
Volts
D.O.
Volts
Operate
Time
NOTES
Check correct indication, trip output, alarm contacts, waveform record.