SA2005P Datasheet, PDF (9/16 Pages) Sames – Programmable Three Phase Power / Energy Metering IC for Stepper Motor / Impulse Counter Applications

SA2005P
PARAMETER DESCRIPTION
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.
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.
Kr is calculated as follows:
Krx=642 000/Rated volt/Rated current/6400x3600x1000/512
The SA2005P’s internal counters count from 0 so 1 must be
subtracted from Kr:
Kr = round(Krx)-1
Where:
Krx is the real value
Kr is the integer value
Kr is made up of 1 byte (D20)
Pre-divider (Cb1, Cb2, Cb3)
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
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
CHB1, CHB2, CHB3 is the measured channel balance %error
that will be corrected
CBMIN is the lowest channel balance %error measured
between the three phases.
sames
LED Pulse-Rate (Cled)
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
0
1
6400 p/kWh
1
0
3200 p/kWh
1
1
1600 p/kWh
0
0
1252 pulses/second @ rated for
fast calibration
Counter Resolution (Cres)
A 13 bit divider divide the pulse rate from the rated conditions
divider down to the desired counter resolution.
Cres is made up of bits 0 of 4 of byte D26 and byte D27.
D26[4:0] D27[7:0] Counter Resolution
Counter Pulse-Width (Pw)
The pulse width for the mechanical counter driver output is
selectable to accommodate various step-motor and impulse-
counter requirements.
Pw is made up of bits 7 and 6 of byte D26.
D26[7] D26[6] Counter Pulse-Width
1
-
284 ms
0
1
142 ms
0
0
71 ms
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.
Cs is made up of bit 7 of byte D16
D16[7]
0
1
Creep threshold
0.02% of rated current
0.01% of rated current
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