Chapter 1) 7SR242 Duobias Description Of Operation
©2015 Siemens Protection Devices Limited
Chapter 1 Page 34 of 60
3.5
Current Protection: High Impedance Restricted Earth
Fault (64H)
Two high impedance restricted earth fault elements are provided, one for each transformer winding
The relay utilises fundamental current measurement values for this function.
The single phase current input is derived from the residual output of line/neutral CTs connected in parallel. An
external stabilising resistor must be connected in series with this input to ensure that this element provides a high
impedance path.
64H Current Setting
sets the pick-up current level. An output is given after elapse of the
64H Delay
setting.
An external series stabilising resistor and a parallel connected voltage limiting non-linear resistor are used with
this function. See ‘Applications Guide’ for advice in specifying suitable component values.
Operation of the high impedance element can be inhibited from:
Inhibit 64H
A binary or virtual input.
User Inhibit
Reylogic (graphical logic).
Figure 3-11
Logic Diagram: High Impedance REF (64H)
Summary of Contents for 7SR242 Duobias
Page 1: ...Answers for energy 7SR242 Duobias Transformer Protection Relay Reyrolle Protection Devices ...
Page 2: ...2 ...
Page 4: ...4 ...
Page 6: ...6 www siemens com energy ...
Page 318: ... 2015 Siemens Protection Devices Limited Chapter 7 Page 2 of 64 ...
Page 324: ... 2015 Siemens Protection Devices Limited Chapter 7 Page 8 of 64 ...
Page 358: ... 2015 Siemens Protection Devices Limited Chapter 7 Page 42 of 64 ...
Page 366: ... 2015 Siemens Protection Devices Limited Chapter 7 Page 50 of 64 ...
Page 380: ... 2015 Siemens Protection Devices Limited Chapter 7 Page 64 of 64 ...
Page 381: ......