You will need
- Technical documentation on the motor.
Identify the type of motor. It could be the motor constant currentor three-phase alternating current. Calculate the nominal current of the motor DC currentin amperes, using the formula: IH=1000PH/(ηHUH), and the nominal current of the motor three-phase currentand using the formula: IH=1000PH/(UHcosφH√ηH), where:Rn is the nominal engine power, kW;UH — the motor rated voltage, V;ηH is the nominal efficiency of the engine;cos Fn is the nominal power factor of the motor. Data on nominal power, nominal voltage, efficiency and power factor take from the technical documentation of the motor.
Calculate the value of the starting currentin amperes after the calculation of its nominal value. To calculate use the formula:IN=IH*KP, where IH is the nominal value of currenta, and KP - the rate constant currentand its nominal value. Review the technical documentation on the motor, it must be specified the multiplicity is constant currentand its nominal value (CP). Multiply this number by the resulting value of the nominal currentand and get the value of starting currentin amperes. Calculate for each motor in the chain.
Pick up a circuit breaker to protect the line of inclusion depending on the magnitude of inrush currentas all the motors in the circuit. Please know that circuit breakers can be type of off, C and D. the Switches with the feature of disconnecting type suitable for lighting networks of General purpose, with the feature disable-type are used for disconnection of lighting circuits and systems with moderate starting current ofAMI (motors and transformers). For circuits with an active-inductive load, and also for protection of electric motors with large starting currentAMI typically used to use switches with characteristics of type D. Identifying the type of switch, adjust depending on the magnitude of the inrush current.
Plug-in circuit breakers with characteristic type With overload capacity magnetic circuit breaker twice as high compared to circuit breakers with characteristic type b
Advice 2 : How to calculate engine power
To find the power of the engine of internal combustion) car, set it on a special stand, which will give its maximum power. If this is not possible, it is possible to calculate the power of the engineby measuring the dynamics of acceleration to 100 km/h after learning his ground in the Datasheet. Determination of the power of electroengine produce at his size, or measure the voltage and current in its windings, then perform a calculation.
You will need
- stopwatch, the tester, caliper.
The power counting of the internal combustion engine automobilecar a rule, the maximum power of the engine of the vehicle indicated in the technical documentation, but with the development of the resource engine, its power decreases. To find her, driving the car on a special stand, where experts measure the power of the engine at the moment.
If this is not possible, find out from the registration certificate of the car's weight, calculate the weight filled him with fuel and driver, and then quickly accelerate the vehicle to 100 km/h, recording a time of acceleration in seconds.
For power counting the overall weight of the car, driver and fuel, multiply by 27.78 (this is the speed of 100 km/h converted to meters per second) squared, and divide by twice the value of acceleration P=27,782*m/(2*t). Get the power value in watts. In order to convert it to kilowatts, multiply by 1000. To translate a value in horsepower, power in kilowatts divide by 0,735.
Counting power electromotorconnect the motor to a source of electrical current with a known voltage. Tester, measure the amperage on each of its windings. Measurement spend in amperes. Find the sum of the currents in all the windings. The resulting value will be multiplied by the voltage of the source current: P=UI. This will be the consumed power electroengine.
To determine the power of the engine by its size, measure the diameter of the stator core and its length. The measurement produced in centimeters with a tape measure and a caliper. Determine the synchronous speed of the shaft and the network where is connected the engine.
Define constant pole division. Multiply the diameter at a synchronous frequency and the number 3.14 and divide the result by the product of the network frequency and the number 120 (3,14*D*n/(120*f)). At the polar division and number of poles determine the constant C for this engineusing the table. Calculate its power, multiplying constant, the square of the shaft diameter, the length of the casing, a synchronous speed and the number 10^(-6): P = C*D2*l*n*10^(-6). The calculation will be derived in kilowatts.