Laurel Electronics LT: 4-20 mA & Serial Data Output Transmitter for AC Phase Angle & Power Factor - Manual

LAUREL ELECTRONICS INC. , 3183-G Airway Ave., Costa Mesa, CA 92626, USA • Tel 714-434-6131 • www.laurels.com 1
LAUREL
ELECTRONICS, INC.
4-20 mA & Serial Data Output Transmitter
for AC Phase Angle & Power Factor
Features
• Transmits phase angle between two AC wave shapes of similar period
• Transmits power factor from 1.000 to 0.000 with sinusoidal signals
• For frequencies from 0.005 Hz to 10 kHz, voltages from 10 mV to 250V AC
• Phase angle resolution of 1°, 0.° or 0.01°
• Phase angle accuracy of 0.01% at AC line frequency
• 4-20 mA or 0-10V transmitter output, jumper selectable, isolated
• Analog output resolution 0.0015% of span (16 bits), accuracy ±0.02% of span
• RS232 or RS485 serial data output, half or full duplex, isolated
• Modbus RTU, Modbus ASCII or Laurel ASCII protocol
• Dual solid state relays for alarm or control, isolated
• Universal AC power, 85-264 Vac, or low voltage power, 10-48 Vdc or 12-32 Vac
Description
Phase Angle Measurement
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 Laureate 4-20 mA 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, 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. 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.
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, power factor is the cosine of phase
angle.
The Laureate 4-20 mA 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
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.
Standard features of Laureate transmitters include:
• 4-20 mA, 0-20 mA or 0-10V analog transmitter output,
isolated, jumper-selectable and user scalable. All selections
provide 16-bit (0.0015%) resolution of output span and 0.02%
output accuracy of a reading from -99,999 to +99,999 counts
that is also transmitted digitally. Output isolation from signal
and power grounds eliminates potential ground loop problems.
The supply can drive 20 mA into a 500Ω (or lower) load for
10V compliance, or 10V into a 5 kΩ (or higher) load for 2 mA
compliance.
• Serial communications output, isolated. User selectable
RS232 or RS485, half or full duplex. Three protocols are user
selectable: Modbus RTU, Modbus ASCII, or Laurel ASCII.
Modbus operation is fully compliant with Modbus Over Serial
Line Specification V1.0 (2002). The Laurel ASCII protocol
allows up to 31 Laureate devices to be addressed on the
same RS485 data line. It is simpler than the Modbus protocol
and is recommended when all devices are Laureates.
• Dual solid state relays, isolated. Available for local alarm or
control. Rated 120 mA at 130 Vac or 170 Vdc.
• Transducer excitation output, isolated. User selectable
5V@100 mA, 10V@120 mA or 24V@50 mA.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or
12-32 Vac power is optional.
Easy Transmitter programming is via Laurel'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 Laurel
(P/N CBL04).