# how to measure 3 phase current

A wattmeter is an equipment used to measure power in a circuit.

Total power in balanced load = 3 x Power per Phase. Here, it is applied to three phase four wire systems, current coil of all the three wattmeters marked as 1, 2 and 3 are connected to respective phases marked as 1, 2 and 3. Mathematically we can write, In this method we have two types of connections. For example, if you assume conductor A as the lead, conductor B is delayed one-third of a cycle in comparison to A and conductor C is delayed two-thirds of a cycle in comparison to A. A comparison between the methods of measuring power in a three-phase circuit is shown in the table below. A balanced load is a load that draws the same current from each phase of the three-phase system, while an unbalanced load has at least one of those currents different from the rest. 4 SCB Configurations, What is an Electrical Fuse? What is welding cable?

Two Wattmeter Method of Power Measurement, Two Wattmeter Method – Balanced Load Condition, https://circuitglobe.com/linear-variable-differential-transformer-lvdt.html, Circuit Analysis of 3 Phase System – Balanced Condition, Phasor Method for Solving Parallel Circuits, Generation of 3 Phase Power in 3 Phase Circuits, Advantages of 3 Phase Over Single Phase System, Difference Between Physical and Chemical Change, Difference Between Alpha, Beta and Gamma Particles, Difference Between Electrolytes and Nonelectrolytes, Difference Between Electromagnetic Wave and Matter Wave, Difference Between Kinetics and Kinematics, Difference Between Synchronous and Asynchronous Counter, Difference Between Analog and Digital Signals, Difference Between Stationary and Progressive Waves, Difference Between Positive and Negative Feedback. Three wattmeter method is used to measure power in 3 phase, 4-wire circuits.

https://circuitglobe.com/linear-variable-differential-transformer-lvdt.html. In special cases, when this method is necessary to use, an ‘artificial star’ can be formed. In this method of three-phase power measurment, the current coil is connected in any one line and the pressure coil is connected alternatively between this and the other two lines. When the load is star connected load, the diagram is shown in below-

Save my name, email, and website in this browser for the next time I comment. The pressure coil is connected across the two points whose. The total power in a three wattmeter method of power measurement is given by the algebraic sum of the readings of three wattmeters.

Facts Everyone Should Know About Trailer Wires, 2 Important Distribution Transformer Testing Methods. For measuring the power in a 3 phase or Poly Phase system, more than one wattmeter is required, or more than one readings are made by one wattmeter. Required fields are marked *. For three phase amperage - FORGET the term "Total Current".

This article explains the measurement of three-phase power in star connected or delta connecter load using the wattmeter methods.

It can be used to measure power in star/delta connected load in balanced or unbalanced condition. Now we will explain the measurement three-phase power measurement using three wattmeter method.

Full disclaimer here. DC Ammeter : Construction, Working and Temperature Compensation, What is Shunt Capacitor Bank? The reading of wattmeter one can be written as

In the case of 3 phase, 3 wire star connected load, it is difficult to get a neutral point which is required for connection. Measurement of Three Phase Power: Three Wattmeter Method. The figure above shows the two wattmeter connection of star connected load. Refer the figure below for better understanding. We have three methods to discuss: Let us discuss one by one each method in detail. Therefore, the total power of the circuit can be determined by multiplying the power measured in any one phase by three. The figure below shows the three wattmeter connection of 3 phase, 4 wire star connected load. The current coil having low resistance is connected in series with the load so that it carries the load current. where , W1 = V1*I1 , W2 = V2*I2, W3 = V3*I3. (K-I), regardless the load is balanced or unbalanced.

Hence, three wattmeters are required to measure power in three-phase, four-wire system, whereas, only two wattmeters are required to measure the power in 3 phase, 3 wire system. However, this method can also be employed in a 3 phase, 3 wire delta connected load, where power consumed by each load is required to be determined separately. While using three wattmeter method following difficulty is met with: To measure power it is not necessary to use three wattmeter, even two wattmeters can be used for the purpose.

The power in a three phase load can be measured by following methods: The name of these methods indicates the number of wattmeters used in the measurement of the three-phase power. i.e. The total power in the load is given by the algebraic sum of the readings of the three wattmeters. Used for measurement of 3 phase, 4 wire circuits. If the three phases are reasonably balanced - list that current. Measurement of Three Phase Power | Wattmeter Methods, The current coil is connected in series with the line carrying current.

In electrical engineering, three-phase electric power systems have at least three conductors carrying alternating current voltages that are offset in time by one-third of the period. Where to buy cheap cable for my welding plant? We’ll cover how 3 phases are generated, what a Cycle and Hertz mean, plot the voltage wave form as it’s being generated, calculate our single phase and three phase voltages. They are.

Here in this article, a three wattmeter method of power measurement is discussed. Types, Properties, and Application, Type B Miniature Circuit Breaker ( Type B MCB), Teach Yourself Electricity and Electronics, Things You Should Know About Electromagnetic Flow Meters. Here, it is applied to three phase four wire systems, current coil of all the three wattmeters marked as 1, 2 and 3 are connected to respective phases marked as 1, 2 and 3.

Now we will explain the measurement three-phase power measurement using three wattmeter method. Both balanced and unbalanced loads. Cosine of the angle between voltage and current (Cosϕ).

According to Blondel’s theorem – When power is supplied by the K wire AC system, the number of wattmeters required to measure power is one less than the number of wire i.e. Three-Phase AC Current Measurement Using Current Transformer Reference Design 4 System Design Theory The TIDA-00753 TI Design has been designed to meet high accuracy demands when measuring wide AC current ranges for motors. Used in Balanced 3 phase, 3 wire load circuit. Refer the figure for the connections of a wattmeter. and reading of wattmeter two is We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.

It consists of two types of coils. Three Wattmeter method is employed to measure power in a 3 phase, 4 wire system. The design uses current transformers (CT), which have a very high turns ratio and are used when measuring the primary current range to achieve better linearity. Hence, each wattmeter measures the power in a single phase. In a 3-phase motor, for example, inrush current generally lasts between 75 msec and 150 msec, with a current spike between 500% and 1,200%. You may refer the below mention link for knowing much about the topic. Three-Wattmeter Method of Three-Phase Power Measurement. Except for 3 phase, 4 wire unbalanced load, 3 phase power can be measured by using only Two Wattmeter Method. Nice article. For example, if A = 5.1A, B = 5.0A, C = 5.2A, you would say, "The current is 5.1A" That phrase means the currents are reasonably balanced and 5.1A is an average number. This current can be several times greater than the operating or steady-state current of the motor. This arrangement produces a smoother power flow and permits lower line voltages. For star connected load clearly the reading of wattmeter one is product of phase current and voltage difference (V2-V3).

Potential difference (V) across its pressure coil. In case of delta connected circuits, the difficulty in using this method is due to fact that the phase coils are required to be broken for inserting current coils of wattmeters.

Pressure coils of all the three wattmeters are connected to a common point at neutral line.