SA2005P
ssaammeess
PARAMETER DESCRIPTION
LED Pulse-Rate (Cled)
Refer to the EEPROM memory allocation map as well as the
Signal flow diagram figure 7, for a description of the registers
used in this section.
Two bits of byte D22 allow for the selection of 4 different LED-
Pulse-rates. The LED pulse-width is 10ms. In fast pulse mode,
the pulse-width is set to 71µs.
D22[1]
D22[0] Calibration LED - Output
Rated Condition (Kr)
Kr is used to program the rated condition of the meter. Rated
conditions from less than 10A to several 100A are possible.
The rated conditions divider as well as the pre-divider is used
to compensate for individual phase calibration. The three
phases are calibrated to the phase with the lowest gain.
0
1
1
0
1
0
1
0
6400 p/kWh
3200 p/kWh
1600 p/kWh
1252 pulses/second @ rated for
fast calibration
Kr is calculated as follows:
Counter Resolution (Cres)
Krx=642 000/Rated volt/Rated current/6400x3600x1000/512
A 13 bit divider divide the pulse rate from the rated conditions
divider down to the desired counter resolution.
The SA2005P’s internal counters count from 0 so 1 must be
subtracted from Kr:
Cres is made up of bits 0 of 4 of byte D26 and byte D27.
Kr = round(Krx)-1
D26[4:0] D27[7:0] Counter Resolution
Where:
Counter Pulse-Width (Pw)
Krx is the real value
Kr is the integer value
Kr is made up of 1 byte (D20)
The pulse width for the mechanical counter driver output is
selectable to accommodate various step-motor and impulse-
counter requirements.
Pre-divider (Cb1, Cb2, Cb3)
Pw is made up of bits 7 and 6 of byte D26.
The channel balance (Cb) value is used to balance the three
phases. The rated conditions divider ratio must be calculated.
Error measurements per phase are done with channel balance
values set to zero. The measured error values are used to
correct the error measurements of the three phases. The
rounding error in the rated conditions divider is also
compensated for in the channel balance calculations. One
count on the channel balance value represent 100%/256.
Gain = ((Krx-Kr+1) / Krx) x 100
D26[7]
D26[6] Counter Pulse-Width
1
0
0
-
284 ms
142 ms
71 ms
1
0
Creep current threshold (Ct)
The creep current is expressed relative to the rated current of
the meter. The SA2005P will not meter currents below the
creep current. The creep current is implemented to prevent
the meter from accumulating energy when no load is
connected.
Gain calculates the rounding error made by the rated
conditions divider.
Cb1 = (CHB1 - CBMIN + Gain) x 256 / 100
Cb2 = (CHB2 - CBMIN + Gain) x 256 / 100
Cb3 = (CHB3 - CBMIN + Gain) x 256 / 100
Cs is made up of bit 7 of byte D16
D16[7]
Creep threshold
CHB1, CHB2, CHB3 is the measured channel balance %error
that will be corrected
0
1
0.02% of rated current
0.01% of rated current
CBMIN is the lowest channel balance %error measured
between the three phases.
9/16
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