sames

sames

SA2005P

10/16

http://www.sames.co.za

D16[2]

Counter Resolution

0

0

0

0

1

1

1

1

Total sum all three phases

Only phase 1 measurement

Only phase 2 measurement

Only phase 3 measurement

Absolute sum of all three phases

Only phase 1 measurement

Only phase 2 measurement

Only phase 3 measurement

D16[1]

0

0

1

1

0

0

1

1

D16[0]

0

1

0

1

0

1

0

1

Example of calculating rated conditions and channel

balance values

Meter rating = 80A / 230V (The SA2005P only uses integer

values)

Calculate the rated conditions:

Krx=642 000/Rated volt/Rated current/6400x3600x1000/512

Krx = 642 000/230/80/6400x3600x1000/512

Krx = 38.3327

Krx = 38 (round Krx) - convert to integer

Kr = 38 - 1 = 37

The value 37 is stored in the rated register (Kr).

Calculate the Channel balance values:

During the rated conditions calculation the rated condition

register was rounded and any rounding errors is now taken

into account:

Gain = ((Krx - Kr+1 ) / Krx) x 100

Gain = ((38.3327 - 38) / 38.337) x 100

Gain = 0.8679

The real channel balance errors still need to be measured so

CHB1,CHB2, CHB3 and CBMIN are set to 0 for all phases.

Calculate the Pre-divider values:

Cb1 = (CHB1 - CBMIN + Gain ) x 256 / 100

Cb1 = (0% - 0% + Gain ) x 256 / 100

Cb1 = Gain x 256 / 100

Cb1 = 0.8679 x 256 / 100

Cb1 =2.2218

Convert to integer

Cb1 = 2

At this stage all three channels will be set with the same

values, Cb1= Cb2= Cb3. Store the calculated values in the

EEPROM. Ensure that the SA2005P reload’s its registers from

the EEPROM by means of the reload pin (RLOAD) or power

down the meter and power up again.

The meter is now set up with the correct register values but not

yet calibrated.

The following example shows how to calibrate the meter

Use the rated conditions divider value and the channel

balance values calculated above and program the EEPROM.

Set the programmable adder for a single phase to be

measured. Measure the %error for each individual phase

without changing any of the calibration constants.

%Error=(Measured Energy-Real Energy)/Real Energyx100

The %Error will be worked back into the calculations above.

For the example we will assume a 1.5%, 5.2%, and 3.2% for

the three individual phases. The rated conditions value is

recalculated relative to the phase with the lowest error. Phase

1 has the lowest error so 1.5% = MinError;

Programmable adder mode (SUM)

The SA2005P can be programmed to sum the energy

measurement as follows:

Total sum

This represents the total sum of the energy measured on all

three phases flowing through the current sensors. Negative

energy flow is taken into consideration.

Energy = Energy phase 1 + Energy Phase 2 + Energy

Phase 3

Absolute sum

This represents the sum of the energy measured on all three

phases, regardless of the direction of energy flow through

the current sensors.

Power = abs (Energy phase 1) + abs (Energy phase 2) +

abs (Energy phase 3)

During calibration the device may be programmed to use only

a specific phase for energy measurement. This can be used for

channel balancing.