Skip to main content

Simplest Single Phase Preventor Circuit for Three Phase Motor Potection


For a 3-phase induction motor,Lit is necessary that all the three phases of supply are present while it is on load.
When any one of the fuses goes out, or a phase is missing, the motor will continue to run with two phases only, but it will start drawing a huge current for the same load. This high current may ruin the motor, unless switched off immediately. A single phase preventor circuit avoids such a mishap. With this circuit the motor will not run, unless all the three phases are present. In a 3-phase supply, the voltages are 120 degrees apart from each other. Thus the addition of three phases gives zero voltage. lf any one of the phase goes, voltage present at the summing point equals half the line voltage. ‘ In this circuit, the three phases (R, Y, B) are connected to line neutral, which in turn is connected to the ground of the   circuit. When all three phases are present, voltage at point D is zero. So potential at pin 3 of 1C 741 is also zero, but voltage at pin 2 is nearly 4V. Here 741 is used as a comparator and the voltage at pin 6 is zero. Hence the relay cannot operate. When a phase goes out, voltage at point D goes up to about halt the line voltage. This voltage is divided by 150k and 50k resistors. The voltage at pin 3 is about 8V when 50k potentiometer is properly adjusted. The voltage at pin 6 is about 12V. This base voltage can drive the relay into operating condition. So, the relay would operate when any of the phases goes out.  This relay, when used in the control circuit of the 3-phase motor, or with a circuit breaker, would switch the power oft on operation.



Comments

Popular posts from this blog

NE566 Function Generator Circuit Diagram

The NE566 Function Generator is a Voltage-Controlled Oscillator of exceptional linearity with buf fered square wave and triangle wave outputs. The frequency of oscillation is determined by an external resistor and capacitor and the voltage applied to the control terminal. The Oscillator CAN be programmed over a ten-to-one frequency range by proper selection of an external resistance and modulated over a ten-to-one range by the control voltage, with exceptional linearity.  FMAX = 1 MHz     WIDE 1000:1 Continuous Sweep Possible  NE566 Function Generator Circuit Diagram Pdf Datasheet  Sourced by : Circuitsstream

Transceiver Homebrew QRP SSB 80M Band

Radio communication transceiver is a radio transmitter at the same time the plane doubles as a radio receiver used for communication purposes. It consists of the transmitter and the receiver are assembled in an integrated way. In mulamula generation, the transmitter or receiver or transmitter and receiver sections are assembled separately and is part of a stand sendirisendiri and can work well sendirisendiri Currently employed both parts are integrated in turn. Aircraft simple transmitter consists of an oscillator generating radio vibration and this vibration after vibration boarded with our voice, in a technique called dimodulir radio, then by the antenna is converted into radio waves and transmitted. As we know that the sound waves we can not reach long distances, although its power is quite large, while the radio waves with a relatively small force can reach a distance of thousands of kilometers. In order for our voice can reach a far distance, then our voice superimposed on radio w...

Altec Lansing 353A – power amplifier – vacuum tube type – Circuit diagram 6L6 12AX7

Used tubes – 12AX7 [pre-amplifier, tone control and audio pre-amplifier] – 6L6GC [audio output] Circuit diagram Tube pin-out -6L6 Tube pin-out 12AX7