AC Phase Angle Input 4-20 mA Current Transmitter

The 4-20 mA output of Laureate AC phase angle transmitter indicates the lead or lag in degrees from 0º to 360º between two periodic signals having the same period. In the illustration to the left, phase angle is 360*P1/P. The signals are applied to the Channel A and B inputs of the Laureate dual-channel pulse input signal conditioner board.

Phase angle measurement is commonly used with AC power from 50 Hz to 400 Hz. Phase angle needs to be set to zero to synchronize AC generators. It also applies to the triggering of SCRs and Triacs for power control. The phase angle between AC current and voltage determines power factor. The Laureate phase angle meter and transmitter provide exceptionally fast response and high accuracy for low frequencies, such as AC line frequency.

Phase angle measurement with the Laureate phase angle meter or phase angle transmitter requires that two signals with identical periods be applied to Channels A and B. A display from -180º to +180º is obtained by timing the rising edge of one channel and the falling edge of the other channel, and programming a 180º offset. A resolution of 1º, 0.1º or 0.01º is selectable. Accuracy is 0.01% up to 100 Hz, 0.1% at 1 kHz, and 1% at 10 kHz.

Phase angle is 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

The 4-20 mA analog output is generated by an ultra-linear 12-bit (4096 step) digital-to-analog convert (DAC) whose output span can be adjusted from 0 to ±999,999 counts and zero can be adjusted from -999,999 to +999,999 counts. The analog output has a rated accuracy of ±0.05% of output span. The output update rate for a minimum timing interval is 20/sec at AC line frequencies.

Transmitter programming is via the unit's three-terminal serial port using Laurel's PC-based Instrument Setup Software. This software can be downloaded from this website at no charge. The required transmitter-to-PC interface cable is available from Laurel (P/N CBL03). 

The transmitters are housed in a DIN rail case that is only 22.5 mm (0.89") thick. Signal connections are via detachable screw clamp plug connectors.