LAUREL LAUREATE 2 Series, Руководство пользователя

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METER SCALING
Refer to the above tables for the full scale counts (or displayed digits) produced by the available
full scale input ranges with a scale factor of 1 and an offset of 0. The decimal point can be set
for direct readout in (milli)volts or (milli)amperes. Decimal point selection does not affect the
counts. For example, a 20V input may be displayed as 20.000V or 20000 mV.
The 5A range, designed for use with a 5A current transformer (CT), is scaled to produce 5000
counts with a scale factor of 1 and an offset of 0. Use with a specific CT will require the scale
factor to be set. For example, for an 800A input, 5A output CT, set a scale factor of 1.6. This is
the desired 8000 count display at 5A divided by the default 5000 count display at 5A. Then set
the decimal point to display to 800.0 at 5A.
All scaling methods applicable to DC, process, strain and load cell meters are available with AC
RMS meters.
INTERNAL SHIELD
To reduce noise pickup inside the meter or transmitter, the
RMS board is fitted with a flexible plug-on shield. If necessary,
This shield may be removed for jumper setting, but must be
reinstalled before closing the instrument.
SIGNAL SHIELDING
Signal Source
RMS
Board
Sig High
Sig Low
Earth Ground
Shield around twisted pair
Shielding for noise reduction
AC RMS measurements are susceptible to signal noise. This is especially true when the instru-
ment has a wide bandwidth. To minimize noise pickup, the input signal wiring should utilize a
shielded twisted pair, and the shield should be connected to signal low at the meter, as
illustrated. If signal low is close to earth ground, such as within 2V, signal low can further be
connected to earth ground at the meter, as illustrated.
PROVISION FOR SIGNAL LEVELS CLOSE TO ZERO
It is difficult to obtain meaningful RMS readings of 0 or close to 0 because of electrical noise
pickup. To avoid erroneous very low readings, the RMS board has been programmed to return
0 counts for readings less than
15 counts .
The maximum number of counts is 20000 for the 200.00 mV, 2.0000V, 20.000V, 200.00V,
2.0000 mA, 20.000 mA, and 200.00 mA ranges. The maximum number is 6000 for the 600.0V
range (which is the 2000.0V range for counts purposes), so that 1 count is 0.1V. The maximum
number is 5000 for the 5.000A range (which is the 20.000A for counts purposes), so that 1 count
is 1 mA. If needed, the 15-count limit can be changed using the Custom ASCII protocol.