PEWM-3C Portable three-phase energy standard class 0.1/ 0.2 (for quick check of electricity meters and current transformers)
The three-phase energy standard PEWM-3C is used for a quick on site check of all kinds of electricity meters– for active or reactive energy, two-, three- or four-wire connection. Three voltages and three currents are measured at the same time. The current can be measured either via direct connection (up to 10A) or with three current clamps to 100A.The current clamps are electronically compensated. Error of the electricity meter can be determined. The disc revolutions or the pulses from the electricity meter can be counted with a universal pickup (type EH 11) or manually with the help of a functional button. The registers of the electricity meter can be tested too, a preliminary quantity of energy being preset in this latter case.
As an option, three current clamps to 1000A, or flexible AC current sensors (on the individual photo) to 1000 A, 2000 A or 3000 A and voltage to 600 V are offered additionally. Error of the whole measuring circuit (electricity meter + current transformers) can be determined with the help of these 1000 A clamps.
The transformation ratio of a current transformer can be measured quickly without any disconnections using both 1000 A and 100 A clamps.
Another function of the device is a vector diagram display and an indication of the numerical values of current, voltage and phase shift; this helps the control of the right connection of electricity meters, motors, and other three-phase circuit components. The screen display of the vector diagram can be changed by the operator for 4-wire or 3-wire measurement; the phase-to-phase voltages are indicated in the second mode.
Other functions of the device are power, cos φ and harmonic distortion measurement; drawing of two input signals in real time (two beam oscilloscope). The device is powered from the voltage measuring circuit or from an auxiliary supply. 200 screen displays of error, current transformer or vector diagram measurement can be memorized in a non-volatile memory and transferred to a computer via RS 232.
PEWM-3C is offered in two accuracy class versions:
- Class 0.1 (direct measurement)/ class 0.2 (current clamps)
- Class 0.2 (direct measurement)/ class 0.5 (current clamps)
FUNCTIONS OF PEWM-3C
General measurement
The vector diagram of voltages and currents is drawn on the large graphic display in this mode. The true RMS values of voltage and current, the angle between them, the angle between phase voltages for each phase; the frequency and sequence of rotation are also indicated. This mode can be switched for three-wire of four-wire measurement. The operator presets also the current inputs - direct measurement, 100A CC, 1000A CC.
Error measurement
The device indicates the electricity meter error in [%] and the true value of energy in this mode. The delivery of pulses is traced with a bar-graph.
The pulses or revolutions number “R”, the constant of the electricity meter “C” and the transformation ratio “P/S” are preset by the operator.
The measurement can be changed for two-, three- or four wire connection, for active or reactive energy. The operator can enter the pulses manually or with the help of a pickup.
Register error measurement
An energy amount is preset in this mode. The measurement is started and stopped by the operator using the relevant button. The error of the register is indicated in [%].
Phase shift measurement
The phase angles between two voltages and between voltage and current are indicated in this mode. The power factors of the three phases and the total power factor are also displayed. The measurements are renewed every 2 seconds.
Power measurement
The values of active, reactive, and apparent power of the three phases are indicated, separately and for all three phases. This mode can be switched over for three-wire or four-wire measurement.
The values on the screen are renewed every two seconds.
Transformation ratio
The parameters of a current transformer are measured in this mode. The true RMS values of primary and secondary current, the turn ratio, and the current phase shift are indicated. The primary current is measured always with a 1000A current clamp in the third phase. The secondary current can be measured either with the 100A current clamp or direct measurement, up to 10 A, in first phase.
Harmonics
The harmonic content of each input signal of voltage or current can be measured in this mode. The amplitude in [%] of the 1st harmonic and the initial phase of the odd harmonics up to the 29th are indicated. The value to expand into harmonics is determined by the operator among the 6 input signals. The measurement and the corresponding screen display are renewed every two seconds.
Oscilloscope
Two signals are drawn on-line on the display. The operator selects the signals. Near the waveforms, the true RMS value of the corresponding signal in [V] or [A] is displayed.
Memory
200 electricity meter or current transformer measurements can be stored in a non-volatile memory, and transferred to a computer via RS 232.
The following data are stored: number of electricity meter (alpha-numerically); the current, voltage, and power factor values of the three phases; error of the electricity meter; the transformation ratio, mode.