ADE7953 datasheet(39/68 Pages) AD

39 / 68 page

Data Sheet

ADE7953

Rev. A | Page 39 of 68

ANGLE MEASUREMENT

The ADE7953 can measure the time delay between the current

and voltage inputs. This feature is available on both Current

Channel A and Current Channel B. The negative-to-positive

transitions identified by the zero-crossing detection circuit are

used as a start and stop for the measurement (see Figure 60).

PHASE A

CURRENT

ANGLE_x

PHASE A

VOLTAGE

Figure 60. Current-to-Voltage Time Delay

The ADE7953 provides a time delay measurement on Current

Channel A and Current Channel B simultaneously. The result-

ing measurements are available in the 16-bit, signed registers

ANGLE_A (Address 0x10C) and ANGLE_B (Address 0x10D).

One LSB of the ANGLE_A or ANGLE_B register corresponds

to 4.47 μs (223 kHz clock). This results in a resolution of

0.0807° at 50 Hz ((360 × 50)/223 kHz) and 0.0969° at 60 Hz

((360 × 60)/223 kHz).

The time delay between the current and voltage inputs can be

used to characterize how balanced the load is. The delays between

phase voltages and currents can be used to compute the power

factor on Current Channel A and Current Channel B, respec-

tively, as shown in Equation 38.

⎟

⎠

⎞

⎜

⎝

⎛

kHz

223

360

cos

LINE

ANGLE

(38)

where:

x = A or B.

fLINE is 50 Hz or 60 Hz.

This method of determining the power factor does not take into

account the effect of any harmonics. Therefore, it may not be

equal to the true definition of power factor shown in Equation 37.

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