sames

sames

SA2005P

9/16

http://www.sames.co.za

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.

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.

D26[4:0]

D27[7:0]

Counter Resolution

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.

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

0

0

-

1

0

284 ms

142 ms

71 ms

D16[7]

Creep threshold

0

1

0.02% of rated current

0.01% of rated current

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

D22[1]

D22[0]

Calibration LED - Output

0

1

1

0

1

0

1

0

6400 p/kWh

3200 p/kWh

1600 p/kWh

1252 pulses/second @ rated for

fast calibration