Tyco 1540 - Manual (Page 39)

When setting up the analogue output for a power factor reading, the Reading Top value must be
in one of the left-hand quadrants and the Reading Bottom value must be in one of the right-
hand quadrants.
Hence, if the Reading Top value is set to –0.5, this will be a power factor of 0.5 for power
exported to an inductive load (bottom left-hand quadrant). Conversely, the Reading Bottom
value must be in one of the two right-hand quadrants. If the Reading Bottom value is set to –0.5,
this will be a power factor of 0.5 for power exported to a capacitive load (bottom right-hand
quadrant). Thus a power factor of +1 (for true power imported to a resistive load) is always
included in the analogue output range.
In specifying the Output Top and Output Bottom values, there are two conventions – one for
European areas of influence and one for North American areas. The two conventions are:
Europe Output Top greater or more positive than Output Bottom.
USA Output Top less or more negative than Output Bottom.
The examples below show cases where power is only imported and the load may be either
capacitive or inductive. The Reading Top and Reading Bottom values of zero ensure that the
whole range of possible (import) power factor readings is covered. The unit in the left-hand
example has an analogue output range of +1 to –1 mA and, since the Output Top value (+1 mA)
is more positive than the Output Bottom value (-1 mA), this arrangement complies with the
European convention. The right-hand example shows the North American convention.
In the above symmetrical arrangement, 0 mA corresponds to unity power factor. This is not the
case with the following asymmetrical arrangement.
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Integra 1540, 1000, 0640, 0440, 0340, 0240 Issue 1 04/03