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68
Operation Techniques
assuming the last applicable frequency reading to provide sampling on the input
terminals, and for most applications, measurement data will therefore be incorrect.
As for other parameters, the
PM295
provides both real-time frequency indication
and a sliding average value over the last eight measurements. The average frequency
reading can be viewed via the front panel, and either reading is accessible through
communications, and can trigger setpoint operations.
4.6.5 Phase Rotation
The
PM295
provides indication of the phase rotation order: positive, negative, and
faulty (error). The positive order is considered to be the A-B-C (L1, L2, L3) phase
order, and the negative - the C-B-A (L3, L2, L1) phase order.
A correct indication is provided for all wiring configuration
s, using either four-wire
or three-wire connections. In the event of a 3-wire open delta configuration, the
phase rotation order is defined using the phase A and C voltages.
The phase rotation order can be read via the front panel and used as a trigger for
setpoint operations.
4.6.6 Phase Angles
To assist the user in correct wiring of the phase voltage and current feeders to the
instrument inputs, the
PM295
provides the user with indication of the relative phase
angle between voltage and current on each phase.
Angle readings can be viewed via the front panel only, and are given in the range of
0 to 359
°
. The angle measurement accuracy is about
±
1
°
.
NOTE
Angle measurements are not applicable in the event of a 3-wire connection.
4.7 Time-Of-Use System
4.7.1 TOU System Operation
The
Time-of-Use
(
TOU
) system allows the user to measure energy usage and
extreme (minimum/maximum) demands for up to 16 different tariffs using an
arbitrary tariff structure. The user can easily customize the
TOU
system operation
depending on a billing scheme used.
The
TOU
system billing technique is based on the currently active annual calendar
that assigns for each day of the year the user-selected daily profile. The daily profile