Setting Example - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
tPCrvx, tACrvx, tBCrvx, tCCrvx: These parameters are used by the customer to create the inverse time
characteristic curve. See equation
Technical manual.
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ANSI-EQUATION1261 V1 EN-US
tPRCrvx, tTRCrvx, tCRCrvx: These parameters are used by the customer to create the inverse reset time
characteristic curve. For more information, refer to Technical manual.
HarmRestrainx: Enables freezing of timers of step x from the harmonic restrain function (2nd harmonic).
This function should be used when there is a risk of an unwanted trip caused by power transformer
inrush currents. It can be set to Disabled/Enabled.
8.1.4.2

Setting example

Directional phase overcurrent protection, four steps can be used in different ways, depending on the
application where the protection is used. A general description is given below.
The pickup current setting of the inverse time protection, or the lowest current step of the definite time
protection, must be defined so that the highest possible load current does not cause protection operation.
The protection reset current must also be considered so that a short peak of overcurrent does not cause
the operation of a protection even when the overcurrent has ceased. This phenomenon is described in
Figure 55.
Current I
Reset current
ANSI09000146 V1 EN-US
Figure 55:
Phasor measurement unit RES670
Application manual
35
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B MultPUx
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Pickup current
The IED does not reset
Pickup and reset current for an overcurrent protection
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for the time characteristic equation. For more information, refer to
Line phase current
ANSI09000146-en-1.vsd
Current protection
GUID-20729467-24AB-42F0-9FD1-D2959028732E v1
Time t
Section 8
(Equation 35)
115