As you can imagine with a large proportion of engineering activities, choosing the incorrect tool may have serious implications on the results of your measurements. The information contained below is to help visitors make a more informed decision on a power analyser which is most appropriate for their requirements.
Power is the rate of doing work, or the amount of energy spent per unit of time. The power of an electrical system is calculated by multiplying the measured voltage by the measured current, then integrating and dividing the result over a period of time. In order to calculate the power of an AC electrical system, the periodic time (inverse of the fundamental frequency) must be known. The term “power analysis” simply refers to the process of determining how much power is available.
A power analyzer is an instrument used to measure the rate of power flow in electrical systems. The flow of power is measured in kilojoules per second (J/s) or kilowatts (kW). Electrical power is the rate at which electrical energy is moved between two places in an electrical system per unit of time.
The method used depends on whether DC or AC power is being calculated. AC power is further broken down into three types, see below:
DC power: DC power is calculated by multiplying voltage (Volts) by current (Amps). The resultant power is measured in Watts (W). This is based on Ohm's law, and is true where the flow of current is always in the same direction.
AC power: In an alternating current (AC) circuit consisting of a source and a load, both the current and voltage are sinusoidal at the same frequency. AC power consists of active power, reactive power and apparent power.
The power factor of an AC power system is defined as the ratio of the active power absorbed by the load to the apparent power flowing in the circuit, and is a dimensionless number in the range of −1 to 1. For an induction motor at full load, power factor is typically in the range 0.85 to 0.9.
The fundamental frequency, often referred to simply as the fundamental, is defined as the lowest frequency of a periodic waveform.
In an electric power system, a harmonic of a voltage or current waveform is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency. Harmonic frequencies are produced by the action of non-linear loads such as rectifiers, discharge lighting or saturated electric machines.
The effects of harmonics on electric systems are adverse, with effects including increased heating due to iron and copper losses, and higher audible noise emission.
Electrical energy is the product of power multiplied by the length of time it was consumed. So if we know how much power, in Watts is being consumed and the time, in seconds for which it is used, we can find the total energy used.
Shaft Power is the mechanical power transmitted from one rotating element of a vehicle, ship, and all types of machinery to another and is represented as Wshaft = 2*pi*ṅ*τ or shaft power (W) = 2*pi*Revolutions per second (RPM/60)*Torque (Nm).
As well as calculating electrical power on 1 or more phases, mechanical power and energy, advanced power analysis using the following analysis techniques is also available with the Dewetron power analyzer line: