4.67
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Figure 4.38
Volts/Hertz Element Logic
For volts/hertz tripping, the relay uses a time-integrating element with a
settable operating characteristic. You can set the element to operate as an
inverse-time element; a user-defined curve element (using the SEL-5806 PC
Software); a composite element with an inverse-time characteristic and a
definite-time characteristic; or as a dual-level, definite-time element. In any
case, the element provides a linear reset characteristic with a settable reset
time. The 24TC torque-control setting supervises this element.
The volts/hertz tripping element has a percent-travel operating characteristic
similar to that employed by an induction-disk time-overcurrent element. This
characteristic coincides well with the heating effect that overexcitation has on
generator components.
The element compares the three-phase voltages and uses the highest of the
values for the volts/hertz magnitude calculations. The relay asserts the 24C2
Relay Word bit without time delay when the machine volts/hertz value
exceeds the element pickup setting, and asserts the 24C2T Relay Word bit
after a delay determined by the characteristic setting. The relay tracks the
frequency over the range 15 to 70 Hz.
The Relay Word bit 24C2T is configured to trip the field breaker and the
generator breaker in the factory-default logic (see Trip/Close Logic Settings
for details). You must change the setting if your application requires a
different action. Volts/hertz logic is discussed in the following section.
Figure 4.39 and Figure 4.40 are similar to IEEE C37.102-2006, IEEE Guide
for AC Generator Protection, Figure 4.5.4-1 and Figure 4.5.4-2.
+
-
24D1D
0
Settings
24D2P1
24D1
24D1T
24C2
24C2T
24CR
(V/Hz)
V/Hz
24D2P1
24D2P2
24IP
24D2D2
24CCS=DD
24IP
24D2P2
V/Hz
24CCS=ID
Relay
Word
Bits
24TC
24D2D2
24CCS
V/Hz
24CCS=U
24D2D1
24TC
24D1P
24CCS=I
24D2D1
24IP
24IC
24ITD
24D2P2
24D2D2
SEL
OGIC
Setting
24CR
t
t
t
Switch closed
when 24TC=1
Volts/Hertz Element
Curve Timing and
Reset Timing
Summary of Contents for SEL-700G Series
Page 14: ...This page intentionally left blank ...
Page 22: ...This page intentionally left blank ...
Page 32: ...This page intentionally left blank ...
Page 52: ...This page intentionally left blank ...
Page 106: ...This page intentionally left blank ...
Page 510: ...This page intentionally left blank ...
Page 560: ...This page intentionally left blank ...
Page 578: ...This page intentionally left blank ...
Page 588: ...This page intentionally left blank ...
Page 604: ...This page intentionally left blank ...
Page 634: ...This page intentionally left blank ...
Page 738: ...This page intentionally left blank ...
Page 802: ...This page intentionally left blank ...