AC Power Factor Meter & AC Phase Angle Meter

AC phase angle & power factor meter


  • Programmable to read phase angle or power factor with two waveshapes of identical period
  • Phase angle resolution of 1°, 0.1° or 0.01° and accuracy of 0.03° at AC line frequency
  • Power factor from 1.000 to 0.000 with sinusoidal signals
  • Accepts AC signals from 1 Hz to 10 kHz at voltages up to 250 Vrms
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac powerr
  • Transducer excitation output (isolated)
  • Wide choice of options:
    - 2 or 4 relays, mechanical or solid state (isolated)
    - 1 or 2 analog outputs (isolated)
    - Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)

AC Phase Angle Measurement

Phase angle measurement by digital phase meter
  • Phase angle in degrees indicates the phase lead or lag between two periodic signals of the same period, as determined from their zero crossings. These two signals will typically be the voltage and current applied to a load. As illustrated, the phase angle θ in degrees is +360*P1/P.
  • The Phase Angle & Power Factor Meter computes phase angle θ by timing zero crossings of two signals applied to Channels A and B. The phase angle range is selectable as 0° to 360° or -180° to +180°. Resolution is selectable as 1°, 0.1° or 0.01°. Typical accuracy is 0.01% from 1 Hz to 100 Hz, 0.1% at 1 kHz, and 1% at 10 kHz.

AC Power Factor Measurement

  • The power factor of an AC power system is the ratio of real power in watts (W) divided by apparent power in volt-amperes (VA). For sinusoidal signals differing by a phase angle θ, power factor is cos(θ).
  • The Phase Angle & Power Factor Meter computes power factor as cos(θ) from phase angle θ. Power factor readings can range from 1.000 to 0.000 with three decimal places and an accuracy of 0.1% for sinusoidal signals at 50/60 Hz power line frequency. While power factor is always positive, the meter artificially assigns a minus sign to power factor for negative phase angles, and it sets power factor to 0 for phase angles greater than 90°.

Designed for flexibility

The Phase Angle & Power Factor Meter utilizes the Extended counter main board and the FR dual-channel signal conditioner board, which accepts AC signals from 12 mV p-p to 250 Vrms. Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and single or dual isolated analog output boards. s may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. The display is available with red or green LEDs. The 1/8 DIN case meets NEMA 4X (IP65) specifications from the front when panel mounted. Any setup functions and front panel keys can be locked out for simplified usage and security. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.


AC Power Factor Meter & AC Phase Angle Meter

Phase Angle Mode
Item Displayed Phase angle difference between two waves of same period
Display Units 1°, 0.1°, 0.01°
Frequency Range 0.005 Hz to 10 kHz
Resolution 0.01°, 1 Hz to 100 Hz; 0.1° at 1 kHz; 1° at 10 kHz
Accuracy 0.05° at 50 or 60 Hz
Maximum Timing Interval 200 sec
Power Factor Mode
Item Displayed Power factor between two sine waves of same period
Display Units 1.000 to 0.000
Polarity Negative sign indicates negative phase angle
Frequency Range 0.005 Hz to 10 kHz
Accuracy 0.1% at power line frequencies
Update Rate
Timing Interval Gate time + 30 ms+ 0-2 signal periods
Gate Time Selectable 10 ms to 199.99 s
Time Before Zero Out Selectable 10 ms to 199.99 s (to indicate loss of signal)
Readout 6 LED digits, 7-segment, 14.2 mm (.56"), red or green.
Range -999999 to +999999
Indicators Four LED lamps
Signal ranges Nine AC signal ranges from 12 mVp-p to 250 Vac
Signal ground Common ground for channels A & B
Noise filter 1 MHz, 30 kHz, 250 Hz (jumper selectable) + digital filter
Voltage, standard 85-264 Vac or 90-300 Vdc
Voltage, optional 12-32 Vac or 10-48 Vdc
Frequency DC or 47-63 Hz
Power  consumption (typical, base meter) 1.2W @ 120 Vac, 1.5W @ 240 Vac, 1.3W @ 10 Vdc, 1.4W @ 20 Vdc, 1.55W @ 30 Vdc, 1.8W @ 40 Vdc, 2.15W @ 48 Vdc
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Excitation Output (standard)
5 Vdc 5 Vdc ± 5%, 100 mA
10 Vdc 10 Vdc ± 5%, 120 mA
24 Vdc 24 Vdc ± 5%, 50 mA
Output Isolation 50 Vdc to meter ground
Analog Output (optional)
Output levels 4-20 mA, 0-20 mA, 0-10V, -10 to +10V (jumper selectable)
4-20 mA, 0-20 mA, 0-10V (dual-output option)
Current compliance 2 mA at 10V ( > 5 kΩ load)
Voltage compliance 12V at 20 mA (< 600Ω load)
Scaling Zero and full scale adjustable from -99999 to +99999
Resolution 16 bits (0.0015% of full scale)
Isolation 250V rms working, 2.3 kV rms per 1 min test
Relay types 2 Form C contact relays or 4 Form A contact relays (NO) 2 or 4 Form A, AC/DC solid state relays (NO)
Current Ratings 8A at 250 Vac or 24 Vdc for contact relays 120 mA at 140 Vac or 180 Vdc for solid state relays
Output common Isolated commons for dual relays or each pair of quad relays
Isolation 250V rms working, 2.3 kV rms per 1 min tes
Serial Data I/O (optional)
Board selections RS232, RS485 (dual RJ11 or RJ45 connectors), USB, Ethernet, USB-to-RS485 converter, Ethernet-to-RS485 converter
Protocols Modbus RTU, Modbus ASCII, Modbus TCP (Ethernet), TDM ASCII
Data rates 300 to 19200 baud
Digital addresses 247 (Modbus), 31 (TDM ASCII),
Isolation 250V rms working, 2.3 kV rms per 1 min test
Operating temperature 0°C to 55°C
Storage temperature. -40°C to 85°C
Relative humidity 95% at 40°C, non-condensing
Protection NEMA-4X (IP-65) when panel mounted
Electrical Connections
Signal connections to TDM pulse input batch controller
Optimizing Meter Inputs for Phase Angle & Power Factor Measurement

Phase angle and power factor measurement with the Phase Angle & Power Factor Meter require that two signals of identical periods be applied to Channels A and B. For best accuracy, both signals should have the same amplitude, the signal amplitude should be larger than 1V, and the trigger level should be minimized by selecting the ±12 mV jumper position.

The meter times zero crossings to 0.1 µs resolution over a user-selectable gate time from 10 ms to 199.99 s. By selecting the minimum gate time of 10 ms, the meter update rate will be approximately 20/s for 50/60 Hz AC line frequency. Improved accuracy will be obtained by making the gate time long enough so that multiple cycles are averaged.

Both signals applied to the meter should be mutually isolated by transformer coupling, so that they can then share the same ground in the meter. The current signal is typically obtained from a current transformer (CT). This should ideally be a CT with a voltage output or a current output in the mA range, which can then be converted to a voltage higher than 1V across an external dropping resistor without excessive heat generation.

Using Meters and Counters to Synchronize Motor Generators
Using TDM Meters and Counters to Synchronize Two Motor Generators

Synchronization of two motor generators requires that the two frequencies be identical, that the lines be in phase, and that the line voltages be close to each other. In this illustration, a single dual channel counter measures both frequencies to six-figure accuracy in a few line cycles. Another dual channel counter measures phase angle to 0.1° resolution. Two AC RMS Voltmeters, which offer ranges of 200.00 V and 600.0 V, are used to display the two RMS voltages to 0.1% accuracy.

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