78M6612-IMSLASHFSLASHP datasheet(86/111 Pages) TERIDIAN

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78M6612 Data Sheet

DS_6612_001

Rev. 1.2

4.4.7.1 Fundamental Energy Measurement Variables

The table below describes each transfer variable for fundamental energy measurement. All variables are

signed 32 bit integers. Accumulated variables such as WSUM are internally scaled so they have at least

2x margin before overflow when the integration time is 1 second. Additionally, the hardware will not

permit output values to ‘fold back’ upon overflow.

Address

Name

Description

0x74

W1SUM_X

The sum of Watt samples from each measurement element (In_8 is the

gain configured by IA_SHUNT or IB_SHUNT).

LSB = 1.67380 *10

-13

0x75

VMAX * IMAX / In_8 Wh.

W2SUM_X

0x76

VAR1SUM_X

The sum of VAR samples from each measurement element (In_8 is the

gain configured by IA_SHUNT or IB_SHUNT).

LSB = 1.67380 *10

-13

0x77

VMAX * IMAX / In_8 Wh.

VAR2SUM_X

WxSUM_X is the Wh value accumulated for element ‘X’ in the last accumulation interval and can be

computed based on the specified LSB value.

For example with VMAX = 600V and IMAX = 52A, LSB (for WxSUM_X) is 0.005222 µWh.

4.4.7.2 Instantaneous Energy Measurement Variables

The Frequency measurement is computed using the Frequency locked loop for the selected phase.

IxSQSUM_X and VxSQSUM are the squared current and voltage samples acquired during the last

accumulation interval. INSQSUM_X can be used for computing the neutral current.

Address

Name

Description

0x72

FREQ_X

Fundamental frequency. LSB

587

−

⋅

≈

≡ S

0x78

I1SQSUM_X

The sum of squared current samples from each element.

LSB = 4.1845*10

-14 IMAX2 A2

0x79

I2SQSUM_X

0x7A

V1SQSUM_X

The sum of squared voltage samples from each element.

LSB= 6.6952 * 10

-13 VMAX2 V2

0x7B

V2SQSUM_X

0x7C

V3SQSUM_X

The sum of squared voltage difference samples (V1-V2) between the

elements.

LSB= 6.6952 * 10

-13 VMAX2 V2

0x18

WSUM_ACCUM

This is the roll-over accumulator for WPULSE.

The RMS values can be computed by the MPU from the squared current and voltage samples as follows:

ACC

RMS

LSB

IxSQSUM

⋅

3600

ACC

RMS

LSB

VxSQSUM

⋅

3600

78M6612-IM/F/P Datasheet(PDF) 86 Page - Teridian Semiconductor Corporation

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