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 in degrees is +360*P1/P.
The phase angle transmitter transmits the lead or lag in degrees from 0° to 360° between two periodic signals of the same period. In the illustration to the right, phase angle is 360*P1/P. The signals are applied to the Channel A and B inputs of the dual-channel pulse input signal conditioner board. A resolution of 1°, 0.1° or 0.01° is selectable. Accuracy is 0.01% up to 100 Hz, 0.1% at 1 kHz, and 1% at 10 kHz.
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, power factor is the cosine of phase angle.
The power factor transmitter computes power factor as the cosine of phase angle. 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°.
Phase angle and power factor are determined by timing crystal clock pulses over a specified gate time which is selectable from 10 ms to 199.99 s. By selecting the minimum gate time of 10 ms, the update rate can be up to 20/s for 50/60 Hz AC line frequency. Improved accuracy is obtained by making the gate time long enough so that multiple cycles can be averaged.
Exceptional Accuracy and Stability. transmitters determine frequency by taking the inverse of period as measured with a calibrated quartz crystal time base. This results in extremely accurate and stable 6-digit internal readings (±999,999 counts), which are then processed in software. The analog output is generated by an ultra-linear 16-bit (65,536 step) digital-to-analog converter (DAC) for 0.02% output accuracy. The update rate of the transmitter output is a programmed gate time + 30 ms + 0-2 signal periods. For a 60 Hz signal, the update rate would be 20 per second. Such fast update rates are ideal for alarm and control.
Standard features of LT transmitters include:
Easy Transmitter programming is via TDM's Instrument Setup Software, which runs on a PC under MS Windows. This software can be downloaded from this website at no charge. The required transmitter-to-PC interface cable is available from TDM (P/N CBL04).
|Phase Angle Mode|
|Item Transmitted||Phase angle difference between two waves of same period|
|Transmitted Units||1°, 0.1°, 0.01°|
|Frequency Range||.005 Hz to 10 kHz|
|Resution||.01°, .005 Hz to 100 Hz, 0.1° at 1 kHz, 1° at 10 kHz|
|Accuracy||0.03° at 50 or 60 Hz|
|Maximum Timing Interval||200 sec|
|Power Factor Mode|
|Item Transmitted||Power factor between two sine waves of same period|
|Transmitted Units||1.000 to 0.000, 1.00 to 0.00, or 1.0 to 1.0|
|Polarity||Negative sign indicates negative phase angle|
|Frequency Range||0.005 Hz to 10 kHz|
|Accuracy||0.1% at power line frequencies|
|Signal Types||Sinusoidal AC and square waves|
|Signal Ranges||10 mV to 250 Vac|
|Signal Ground||Common ground for channels A & B|
|Noise Filter||1 MHz, 30 kHz, 250 Hz (selectable)|
|Conversion Interval||Gate time + 30 ms + 0-2 signal periods|
|Gate Time||Selectable 10 ms to 199.99 s|
|Time Before Zero Output||Selectable 10 ms to 199.99 s|
|Analog Output (standard)|
|Output Levels||4-20 mA, 0-20 mA, 0-10 Vdc, -10 to +10Vdc (user selectable)|
|Compliance, 4-20 mA||10V (0-500 ohm load)|
|Compliance, 0-10V||2 mA ( kOhm load)|
|Output Resolution||16 bits (65,536 steps)|
|Output Accuracy||0.02% of output span plus conversion accuracy|
|Output Isolation||250V rms working, 2.3 kV rms per 1 minute test|
|Serial Data Output (standard)|
|Signal Types||RS232 or RS485 (half or full duplex), jumper selectable|
|Data Rates||300, 600, 1200, 2400, 4800, 9600, 19200 baud|
|Output Isolation||250V rms working, 2.3 kV rms per 1 min test|
|Serial Protocols||Modbus RTU, Modbus ASCII, TDM ASCII|
|Modbus Compliance||Modbus over Serial Line Specification V1.0 (2002)|
|Ethernet Connector||RJ45 jack for 10/100 Base-T Ethernet cable|
|RS232/485 Connector||Screw terminals for easy daisy chaining|
|Digital Addresses||247 for Modbus, 31 for TDM ASCII|
|Dual Relay Output (standard)|
|Relay Type||Two solid state relays, SPST, normally open, Form A|
|Load Rating||120 mA at 140 Vac or 180 Vdc|
|Sensor Excitation Output (Standard)|
|Output levels||5V@100 mA, 10V@120 mA, 24V@50 mA (jumper selectable)|
|Output Isolation||50V from signal ground|
|Standard Power||85-264 Vac or 90-300 Vdc|
|Low Power Option||10-48 Vdc or 12-32 Vac|
|Power Frequency||DC or 47-63 Hz|
|Power Isolation||250V rms working, 2.3 kV rms per 1 min test|
|Power Consumption||2W typical, 3W with max excitation output|
|Dimensions||129 x 104 x 22.5 mm case|
|Mounting||35 mm rail per DIN EN 50022|
|Electrical Connections||Plug-in screw-clamp connectors|
|Operating temperature||0°C to 55°C|
|Storage temperature.||-40°C to 85°C|
|Relative humidity||95% at 40°C, non-condensing|
|Cooling Required||Mount transmitters with ventilation holes at top and bottom. Leave 6 mm (1/4") between transmitters, or force air with a fan.|
|Using Meters, Counters or Transmitters to Synchronize 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 (or frequency transmitter) measures both frequencies to six-figure accuracy in a few line cycles. Another dual channel counter (or phase transmitter) 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 voltage to 0.1% accuracy.