Control Elements; Overview - GE G30 Instruction Manual

CONTROL ELEMENTS

For example, a setting of 20% for a 200 MW machine, is 0.20 × 200 MW = 40 MW. If 7.967 kV is a primary VT voltage and 10
kA is a primary CT current, the source pu quantity is 239 MVA, and thus, the pu power setting is 40 MW / 239 MVA = 0.167
pu.
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the measured power is above this setting but below the
operate. If the
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less than the
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This setting applies to three-phase power and is entered in pu. The base quantity is three-phase power on the primary side,
which is calculated as
as 3 x Phase CT Primary x Phase VT Ratio x Phase VT Secondary in case of wye connected VTs.
If the VTs are located on the high-voltage (HV) side of the transformer, then configure the source using CTs that
are also on the HV side. Correspondingly, if the VTs are located on the low-voltage (LV) side of the transformer,
then configure the source using CTs that are also on the LV side. In both cases, the CT polarity produces a
positive power measurement when the machine is generating.
5
5.8 Control elements

5.8.1 Overview

Control elements are used for control rather than protection. See the Introduction to Elements section at the beginning of
this chapter for information.
5-266
— This setting specifies the minimum active power that inhibits this protection function. If
is set to "0.00 pu", then the element does not operate for all power values
setting.
3 x Phase CT Primary x Phase VT Ratio x Phase VT Secondary in case of delta connected VTs and
Figure 5-146: Third harmonic neutral undervoltage logic
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G30 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
setting, the element does not