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CHAPTER 6: SETPOINTS
S3 Protection
Time overcurrent curves
NOTE:
NOTE
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
The 350 protection elements are organized in two identical setpoint groups: Setpoint
Group 1 and Setpoint Group 2.
Figure 6-14: Main Protection menu
The relay has a total of two phase, two neutral, and two ground/sensitive ground time
overcurrent elements. The programming of the time-current characteristics of these
elements is identical in all cases and will only be covered in this section. The required curve
is established by programming a Pickup Current, Curve Shape, Curve Multiplier, and Reset
Time. The Curve Shape can be either a standard shape or a user-defined shape
programmed with the FlexCurve™ feature.
Accurate coordination may require changing the time overcurrent characteristics of
particular elements under different conditions. For picking up a cold load, a different time-
current characteristic can be produced by increasing the pickup current value. The
following setpoints are used to program the time-current characteristics.
If the injected current is more than 20 x PKP, the trip time will be the same as 20 x PKP.
•
<Element_Name> PICKUP: The pickup current is the threshold current at which the
time overcurrent element starts timing. There is no intentional 'dead band' when the
current is above the pickup level. However, accuracy is only guaranteed above a 1.5
per unit pickup level. The dropout threshold is 98% of the pickup threshold. Enter the
pickup current corresponding to 1 per unit on the time overcurrent curves as a
S3 SETPOINT GROUP 1/2
PHASE TOC
PHASE IOC
PHASE DIR OC
GROUND TOC
GROUND IOC
GROUND DIR OC
NEUTRAL TOC
NEUTRAL IOC
NEUTRAL DIR OC
NEGATIVE SEQ IOC
NEGATIVE SEQ TOC
PHASE UV
PHASE OV
NEUTRAL OV
NEGATIVE SEQ OV
AUXILIARY UV
AUXILIARY OV
POS SEQ UV
UNDER-FREQUENCY
OVER-FREQUENCY
THERMAL OVERLOAD
WATT GND FLT
DIR POWER
BROKEN COND
VOLTS-PER-HERTZ
898758A6. cdr
S3 PROTECTION
6–31
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