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True RMS Voltage
The True RMS Voltage parameter is an average of the three true RMS phase to phase voltages for Delta systems.
For Wye systems this parameter is an average of the three true RMS line to neutral voltages.
Volts = Emax X (mA out -4)
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Where,
Volts = True RMS Voltage output
Emax = 170 (SYSTEM VOLTAGE SELECT switch set to 120 - 144 V)
= 320 (SYSTEM VOLTAGE SELECT switch set to 190 - 277 V)
= 470 (SYSTEM VOLTAGE SELECT switch set to 346 - 415 V)
= 550 (SYSTEM VOLTAGE SELECT switch set to 440 - 480 V)
= 700 (SYSTEM VOLTAGE SELECT switch set to 600 V)
= Primary value of potential transformer multiplied by 1.42 (For systems greater than 600 volts)
mA out = PowerTrak milliamp output value for True RMS Voltage
True RMS Current
The True RMS Current parameter is an average of the three true RMS values of the three-phase currents.
Current = CT Primary X (mA out - 4)
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Where,
Current = True RMS Current
CT Primary = Primary value of the CT ratio selected with DIP switch C1-C5. ( ex. CT ratio = 500 for 500:5 ratio)
mA out = PowerTrak milliamp output value for True RMS Current
DIGITAL OUTPUTS
KWH Pulse Output
The PowerTrak provides a contact closure pulse output representing energy consumption (KWH). By setting the
appropriate DIP switches (B1-B2, See Table 3) each pulse will represent either 10, 1, 0.1 or 0.01 KWH per pulse.
The ”10“ KWH per pulse setting produces the slowest pulse rate and the ”0.01“ KWH per pulse setting produces the
fastest pulse rate. Select a KWH per pulse setting that produces a pulse rate that can be read by the building
automation controller (or other data acquisition equipment) and will not exceed five pulses per second at the maxi-
mum expected KW value. See KWH equations. The ”KWH PULSE“ LED is ”ON“ when the KWH pulse contact is
closed and ”OFF“ when the contact is open.
KWH equations:
Three phase and single phase equation:
KWH = N x KWH per pulse x PT Ratio (If used)
Where,
N = total number of pulses accumulated at the controller input
KWH per pulse = KWH per pulse setting at DIP switches B1-B2 (See Table 3).
PT Ratio=PT Primary/PT Secondary. Example: 4800V to 120V PT Ratio=4800/120=40
EQUATIONS - continued
