1. Presented by :- Rahul pawar

2. 1.In normal life if we are operating any electrical appliance working in a 3 phase
condition and because of some electrical problem they are not working so our project
will guide us to know which phase is not present and lead to OFF of the appliances.
2.Three phase fault detector projects equipment mostly motors from destructive line
conditions. When one of the 3 phases goes off the 3 phase fault detector/analyzer
detects and the buzzer starts operating and the relay gets connected to the motor and
the motor is prevented from getting damaged.
3.The output of the relay can be used either in set mode or reset mode , as well as the
output of the relay can be used anywhere 3 phase supply is needed like heavy
machines , power supplies etc.
4. The linear advantage of this circuit is that it cans automatically saves the complete
system being get damaged automatically as well as it also provides a check on the
phase which gets start after the disruption.

3. In an electric power system, a fault is any abnormal electric current. For
example, a short circuit is a fault in which current bypasses the normal
load. An open-circuit fault occurs if a circuit is interrupted by some
failure. In three-phase systems, a fault may involve one or more phases
and ground, or may occur only between phases. In a "ground fault" or
"earth fault", charge flows into the earth. The prospective short circuit
current of a fault can be calculated for power systems. In power systems,
protective devices detect fault conditions and operate circuit
breakers and other devices to limit the loss of service due to a failure. The
ckt consists of 3 rectifier circuit which connected in parallel to the relay
through the LEDs. A capacitor is connected in parallel of the rectifier. 3
transistors are also connected to the relay through their collector in
series. The base of the transistors are connected to the +ve terminal of
capacitors through a resistance and the emitter of the transistors are
connected to the ground. The Relay is connected to the alarm. Rectifiers
which are connected to the main supply. The 230v main ac supply is step

4. CIRCUIT DIAGRAM AND
DISCRIPTION
Fig. 1 CIRCUIT DIAGRAM OF 3 PHASE
FAULT DETECTOR

5. CIRCUIT DESCRIPTION
According to circuit diagram there are 3 rectifiers circuit for 3 phases. They
consist diode D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, D12,and the
supply is given in between D1,D3 and D2,D4. The capacitor C1,C2 and C3 are
connected in parallel of each rectifier. LEDs are connected in between the NC
point of relay and the rectifier’s output with parallel in each other. The base of
the transistors Q1, Q2, and Q3 from the rectifier’s output through the
resistances R4, R5 and R6. The Emitter and the collector of Q1, Q2 and Q3 are
connected in series with each other from ground to NC point relay. The alarm is
connected to COMM point of relay when the supply is given in the rectifier of R
phase. In +ve half cycle the diode D1 and D4 are conduct and give the output
on the terminal. In the other
-ve half cycle the diode D2 and D3 is conduct and rectify the half cycle. This
rectified output is appear on the terminal of the capacitance C1 and it is start
charging with +ve polarity. When the capacitor C1 is charged current is start
flowing through R1 and LED D6 and also start flowing to the base of the
transistor Q1 through resistance R4. The collector of the Q1 is connected to the
relay and the emitter of Q1 is connected to collector of Q2 and the current
flowing through Q1 to Q2. This description is also similar for the other two
phases.

6. WORKIN
G
The ckt consists of 3 rectifier circuit which connected in parallel to the relay through the
LEDs. A capacitor is connected in parallel of the rectifier. 3 transistors are also
connected to the relay through their collector in series. The base of the transistors are
connected to the +ve terminal of capacitors through a resistance and the emitter of the
transistors are connected to the ground. The Relay is connected to the alarm. Rectifiers
which are connected to the main supply. The 230v main ac supply is step down to the
required level by the use of step down transformer. If all the 3 phase are present the
LEDs are glowing and alarm is in off condition. Here the transistors are works as a
switch. Because when the voltage of Base of the transistors is greater than the voltage
of the Collector of the transistors, so the current is flows from Collector to emitter and the
relay set on NC and no current flow through the alarm. Suppose if one or two phase are
gone than the supply of the faulty phase is off and the capacitor is start discharging
through resistance and transistor when capacitance discharge completely a large
reverse voltage is applied on the LED and it goes off and the voltage of the Base of the
transistor is low as compare to Collector and the transistor is comes in off condition due
to these the supply of the relay is break and the relay’s NC point is comes in NO
condition and due to this the alarm is connect to the main supply and it start ringing.

7. ADVANTAGES AND
DISADVANTAGES
1.Rapid Results – It is quick and easy to
configure, giving results in seconds
2.Reliability and Ease of Use – It produces
high quality results with high repeatability
allowing for rapid and reliable decision
making
3.Rugged and Reliable – It is a circuit with
outstanding durability for field use
Simple User-friendly interface

8. LIMITATIONS:
1.It is only useful for house-hold or
low voltages up to 230 volts
2.It is not usable for H.T Lines

9. APPLICATI
ON
Identify and locate – Faults & defects in any of the 3 on
line phases.
Condition based monitoring of faults, in line variations,
during commissioning
And while in-service.
It can be used by itself or in conjunction with
Other in-service test results for assisting in decision
making process or switching.