EEP 303 lab report

1. EEP303-Experiment 5
NEGATIVE PHASE SEQUENCE RELAY
Submitted By:
CIDDHI JAIN-2010EE50011
INDRA BHUSHAN-2010EE50548
MEHUL MITTAL-2010EE50553
SHRISTI MAHAJAN-2010EE50561
UMANG GUPTA-2010EE50564
VIVEK MANGAL2010EE50566

2. AIM:
1. To study the construction of a typical negative phase sequence relay.
2. To experimentally verify the calibration of the typical negative phase sequence relay.
APPARATUS:
1. Negative phase sequence relay. Time setting-9sec
2. Current transformers – 2 nos.
3. Rheostats
4. Ammeters
Circuit Diagram:

3. OBSERVATIONS:
The first fault was done in R-Y line in which both the current transformer was working in the
circuit.
Ammeter Reading:
I=0.9 A
The negative sequence current is I/√3=0.51 A . This is greater than relay current threshold of
0.5 A. The relay tripped after 9sec.
I=0.5 A
The negative sequence current is I/√3=0.3 A . This is lesser than relay current threshold of
0.5 A. The relay didn’t tripped.
The relay functioned correctly. The connections and theory was verified. The time for
tripping is kept high so as to neglect initial transient current in the circuits.
Next fault was done in B-R line in which only one the current transformer was working in the
circuit. Other C.T. was removed
Ammeter Reading:
I=0.9 A
The negative sequence current is I/√3=0.51 A . This is greater than relay current threshold of
0.5 A. The relay tripped after 9sec.