Power Analyzers

A power analyzer is used to measure the rate of power flow in electrical systems, and power parameters including power factor, efficiency and harmonics. Our power analyzers are ideal for high accuracy power measurement over a wide frequency range. Power measurement is from 4 channels to 32 channels, with optional speed and torque inputs, to measure both electrical and mechanical power. Power measurement features gapless cycle by cycle detection, to ensure no blind spots. Hence, this is ideal for testing during dynamic load changes, where traditional power meters fail. Analysis features include real time efficiency mapping, DQ analysis. There are options for data transfer to a test cell controller in a range of digital formats. All systems include the latest power analysis software for setup, real time visualisation, post processing and reporting. Applications include electric and hybrid vehicle drivetrain development, renewable energy measurement and transformer testing.

Download power analyzers overview POWER ANALYZERS OVERVIEW

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Choosing the Right Type of Power Analyzer

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.

  • Active power: Active power AKA real power is the amount of power that is actually consumed in an AC circuit. Active power is the instantaneous voltage multiplied by current averaged over the fundamental period. Thus to calculate active power, the fundamental frequency must also be measured.
  • Reactive power: The reactive power (kVAR) establishes the magnetic field in the motor that enables it to operate. It represents the amount of power that continuously bounces back and forth between the source and load meaning the power which cannot be used for effective work in an AC circuit or system. It is the difference between active and apparent power.
  • Apparent power: Apparent power is the vector sum of active and reactive power, and is the product of the RMS values of voltage and current over the fundamental period.

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:

  • Inverter, electrical machine (motor) and total efficiency calculation
  • Speed-torque efficiency mapping
  • Harmonics and FFT data
  • DQ analysis (Park-Clarke transformation)
  • Drive cycle power and energy measurement, e.g. WLTP
  • Synchronised vibration and sound measurement
  • Digital interface – CAN, EtherCAT, Ethernet.