1MAC309294-MB F
Section 4
Protection functions
RER620
225
Technical Manual
Figure 102:
Functional module diagram
Underfrequency detection
The underfrequency detection measures the input frequency calculated from the voltage
signal. An underfrequency is detected when the measured frequency drops below the set
value of the
Start Value Freq
setting.
The underfrequency detection module includes a timer with the Definite Time (DT)
characteristics. Upon detection of underfrequency, operation timer activates the
ST_FRQ
output. When the underfrequency timer has reached the value set by
Operate Tm Freq
, the
OPR_FRQ
output is activated if the underfrequency condition still persists. If the
frequency becomes normal before the module operates, the reset timer is activated. If the
reset timer reaches the value set by
Reset delay time
, the timer resets and the
ST_FRQ
output is deactivated.
df/dt detection
The df/dt detection measures the input frequency calculated from the voltage signal and
calculates its gradient. A high df/dt condition is detected by comparing the gradient to the
Summary of Contents for RER620
Page 2: ......
Page 22: ...Section 1MAC309294 MB F 16 RER620 Technical Manual ...
Page 88: ...Section 3 1MAC309294 MB F Basic functions 82 RER620 Technical Manual ...
Page 278: ...Section 4 1MAC309294 MB F Protection functions 272 RER620 Technical Manual ...
Page 362: ...Section 5 1MAC309294 MB F Control functions 356 RER620 Technical Manual ...
Page 418: ...Section 7 1MAC309294 MB F Measurement functions 412 RER620 Technical Manual ...
Page 428: ...Section 8 1MAC309294 MB F Recording functions 422 RER620 Technical Manual ...
Page 464: ...Section 9 1MAC309294 MB F Other functions 458 RER620 Technical Manual ...
Page 554: ...Section 10 1MAC309294 MB F General function block features 548 RER620 Technical Manual ...
Page 568: ...Section 12 1MAC309294 MB F Relay physical connections 562 RER620 Technical Manual ...
Page 574: ...Section 13 1MAC309294 MB F Technical data 568 RER620 Technical Manual ...
Page 576: ...Section 14 1MAC309294 MB F Relay and functionality tests 570 RER620 Technical Manual ...
Page 578: ...Section 15 1MAC309294 MB F Applicable standards and regulations 572 RER620 Technical Manual ...
Page 582: ...Section 16 1MAC309294 MB F Glossary 576 RER620 Technical Manual ...
Page 583: ......