ADE7816 datasheet(28/48 Pages) AD

28 / 48 page

ADE7816

Data Sheet

Rev. 0 | Page 28 of 48

As shown in Figure 34, the OV bit (Bit 18) in the STATUS1 register

(Address 0xE503) is set to 1 if the ADE7816 detects an overvoltage

condition. The overcurrent detection feature works in a similar

manner; however, a group of current channels (A, B, C or D, E, F)

must be selected by Bit 14 (CHANNEL_SEL) of the COMPMODE

Group section). When switching between current channel groups,

no additional settling time is required and the feature continues to

monitor at an 8 kHz rate. If an overcurrent condition is detected on

any of the selected current channels, the OI bit (Bit 17) of the

STATUS1 register is set to 1. To determine the current channel(s)

causing the overcurrent event, the OICHANNELx bits (Bit 3, Bit 4,

and Bit 5) of the CHSTATUS register are used.

Setting the OVLVL and OILVL Registers

The content of the overvoltage (OVLVL) and overcurrent (OILVL),

24-bit, unsigned registers is compared to the absolute value of

the voltage and current channels. The maximum value of these

registers is 5,928,256 (0x5A7540) with full scale inputs. When

either the OVLVL or OILVL register is equal to this value, the

overvoltage or overcurrent conditions are never detected.

Writing 0x0 to these registers signifies that the overvoltage or

overcurrent conditions are continuously detected, and the

corresponding interrupts are permanently triggered.

Overvoltage and Overcurrent Interrupts

Two interrupts are associated with the overvoltage and overcurrent

features. The first interrupt is associated with the overvoltage

feature; it is enabled by setting the OV bit (Bit 18) of the MASK1

condition causes the external IRQ1 pin to be pulled low. A second

interrupt is associated with the overcurrent detection feature.

This interrupt is enabled by setting the OI bit (Bit 17) of the

MASK1 register. When this bit is set, an overcurrent condition

on any of the selected current channels causes the external

IRQ1 pin to be pulled low.

INDICATION OF POWER DIRECTION

The ADE7816 includes sign indication on the active and reactive

power measurements. Sign indication allows positive and negative

energy to be identified and billed separately, if required. It also

helps detect a miswiring condition. This feature is available on

three channels at a time. A group of current channels (A, B, C

or D, E, F) must be selected by Bit 14 (CHANNEL_SEL) of the

COMPMODE register at Address 0xE60E (see the Selecting a

Current Channel Group section).

The three-sign indication bits that indicate the polarity of the

active power are Bit 0 (W1SIGN), Bit 1 (W2SIGN), and Bit 2

(W3SIGN) of the CHSIGN register (Address 0xE617). W1SIGN

indicates the direction of power on the A or D current channel,

W2SIGN indicates the direction of power on the B or E current

channel, and W3SIGN indicates the direction of power on the C

or F current channel. An additional three bits, VAR1SIGN (Bit 4),

VAR2SIGN (Bit 5), and VAR3SIGN (Bit 6), also in the CHSIGN

bits are unlatched and read only. A low reading (0) on any of

these bits indicates that the corresponding power reading is

positive; a high reading (1) indicates that the corresponding

power reading is negative.

In addition to the sign indication bits, the ADE7816 also includes

reverse power status bits and associated interrupts. The status bits

are located in the STATUS0 register (Address 0xE502). The reverse

power bits are set to 1 when the sign of the power changes. Bit 6

(REVAP1) monitors the A or D current channel, Bit 7 (REVAP2)

monitors the B or E channel, and Bit 8 (REVAP3) monitors the

C or F current channel. Similarly, Bit 10 (REVRP1), Bit 11

(REVRP2), and Bit 12 (REVRP3) monitor the reactive power.

Both positive-to-negative and negative-to-positive changes result

in the corresponding status bit being set. Each status bit has a cor-

responding interrupt enable bit that is located in the MASK0

a change in active energy power direction causes the external IRQ0

pin to be pulled low (see the Interrupts section for more details).

ANGLE MEASUREMENTS

The ADE7816 can measure the time delay between the current

and voltage inputs. It can also be configured to measure the time

between the six current channels. The negative-to-positive

transitions identified by the zero-crossing detection circuit are

used as a start and stop for the measurement (see Figure 35).

CURRENT

CHANNEL X

ANGLE

VOLTAGE

Figure 35. Voltage-to-Current Time Delay

There are three angle registers that store the results of the time

delay. A group of current channels (A, B, C or D, E, F) must be

selected by Bit 14 (CHANNEL_SEL) of the COMPMODE

When Bits[10:9] (ANGLESEL) of the COMPMODE register are

set to 00b (default), the time delays between the current channels

and the voltage channel are measured. The ANGLE0 register

(Address 0xE601) stores the delay between the voltage and the

A or D current channel. The ANGLE1 register (Address 0xE602)

stores the delay between the voltage and the B or E current

channel. The ANGLE2 register (Address 0xE603) stores the delay

between the voltage and the C or F current channel. 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, as shown

in Equation 16.

















kHz

256

360

cos

LINE

ANGLEx



(16)

where fLINE is 50 Hz or 60 Hz.

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