S3 PROTECTION
Voltage elements
S3 SETPOINT GROUP 1
PHASE TOC
PHASE IOC1
PHASE IOC2
▼
GROUND
TOC
GROUND IOC1
GROUND IOC2
GND DIR
NEUTRAL TOC
NEUTRAL IOC1
NEUTRAL IOC2
NTRL DIR
NEG SEQ IOC
PHASE UV
PHASE OV
NEUTRAL OV
NEGATIVE SEQ OV
AUXILIARY UV
AUXILIARY OV
UNDER-FREQUENCY1
UNDER-FREQUENCY2
OVER-FREQUENCY1
OVER-FREQUENCY2
THERMAL MODEL
898759A1.cdr
Phase undervoltage
6–90
Courtesy of NationalSwitchgear.com
Figure 27: Voltage elements menu
S3 NEUTRAL OV
NTRL OV FUNCTION
▼
NTRL OV
PKP
NTRL OV
DELAY
OUTPUT RELAY 3
...
OUTPUT RELAY 6
BLOCK 1
BLOCK 2
BLOCK 3
S3 AUXILIARY OV
AUX OV FUNCTION
S3 UNDERFREQUENCY 1/2
▼
UNDRFREQ 1/2 FUNC
AUX OV PKP
▼
AUX OV DELAY
UNDRFREQ 1/2 PKP
OUTPUT RELAY 3
UNDRFREQ 1/2 DELAY
...
MIN VOLTAGE
OUTPUT RELAY 6
OUTPUT RELAY 3
BLOCK 1
...
BLOCK 2
OUTPUT RELAY 6
BLOCK 3
BLOCK 1
BLOCK 2
BLOCK 3
S3 OVERFREQUENCY 1/2
OVERFREQ 1/2 FUNCTN
▼
OVERFREQ 1/2 PKP
OVERFREQ 1/2 DELAY
OUTPUT RELAY 3
...
OUTPUT RELAY 6
BLOCK 1
BLOCK 2
BLOCK 3
•
Undervoltage Protection: For voltage sensitive loads, such as induction motors, a
drop in voltage will result in an increase in the drawn current, which may cause
dangerous overheating in the motor. The undervoltage protection feature can be used
S3 PHASE UV
PH UV FUNCTION
▼
PH UV
PH UV CURVE
S3 PHASE OV
PH UV
PH OV FUNCTION
PH UV PHASES
▼
PH UV MIN VOLTAGE
PH OV
PKP
OUTPUT RELAY 3
PH OV
DELAY
...
PH OV PHASES
OUTPUT RELAY 6
OUTPUT RELAY 3
BLOCK 1
...
BLOCK 2
OUTPUT RELAY 6
BLOCK 3
BLOCK 1
BLOCK 2
BLOCK 3
S3 AUXILIARY UV
AUX UV FUNCTION
▼
AUX UV
PKP
AUX UV CURVE
AUX UV
DELAY
AUX UV MIN VOLTAGE
OUTPUT RELAY 3
...
OUTPUT RELAY 6
BLOCK 1
BLOCK 2
BLOCK 3
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS
PKP
DELAY
S3 NEGATIVE SEQ OV
NEG SEQ OV FUNCTN
▼
NEG SEQ OV
PKP
NEG SEQ OV
DELAY
OUTPUT RELAY 3
...
OUTPUT RELAY 6
BLOCK 1
BLOCK 2
BLOCK 3