ADE7953 datasheet(40/68 Pages) AD

40 / 68 page

ADE7953

Data Sheet

Rev. A | Page 40 of 68

NO-LOAD DETECTION

The ADE7953 includes a no-load detection feature that eliminates

“meter creep.” Meter creep is defined as excess energy that is

accumulated by the meter when there is no load attached. The

ADE7953 warns of this condition and stops energy accumula-

tion if the energy falls below a programmable threshold. The

ADE7953 includes a no-load feature on the active, reactive, and

apparent energy measurements. This allows a true no-load

condition to be detected and also prevents creep in purely

resistive, inductive, or capacitive load conditions. The no-load

feature is enabled by default.

SETTING THE NO-LOAD THRESHOLDS

Three separate 24-/32-bit registers are available to set the

no-load threshold on the active, reactive, and apparent

energies: AP_NOLOAD (Address 0x203 and Address 0x303),

VAR_NOLOAD (Address 0x204 and Address 0x304), and

VA_NOLOAD (Address 0x205 and Address 0x305). The active,

reactive, and apparent energy no-load thresholds are completely

independent and, therefore, all three thresholds are required.

The no-load thresholds for all three measurements can be set

based on Equation 39.

536

X_NOLOAD

−

(39)

where:

X is AP, VAR, or VA.

Y is the required threshold amplitude with reference to

full-scale energy (for example 20,000:1).

As shown in Equation 39, the no-load threshold can be config-

ured based on the required level with respect to full scale. For

example, if a no-load threshold of 10,000:1 of the full-scale

current channel is required and the voltage channel is set up to

operate at ±250 mV (50% of full scale), then a value of 20,000 is

required for Y. A default value of 58,393 (decimal) is programmed

into the AP_NOLOAD and VAR_NOLOAD registers, setting

the initial no-load threshold to approximately 10,000:1. The

VA_NOLOAD register has a default value of 0x00.

The no-load thresholds AP_NOLOAD, VAR_NOLOAD, and

VA_NOLOAD must be written before enabling the no-load

feature. The no-load feature is enabled using the DISNOLOAD

disable the no-load detection, modify the threshold, and then

reenable the feature using the DISNOLOAD register.

Although separate no-load interrupts are available for Current

Channel A and Current Channel B (phase and neutral current),

the same no-load level is used for both. For example, if the

VAR_NOLOAD level is set to 0.05% of full scale, this value is

the reactive power no-load threshold used for both Current

Channel A (phase) and Current Channel B (neutral).

ACTIVE ENERGY NO-LOAD DETECTION

Active energy no-load detection can be used in conjunction with

reactive energy no-load detection to establish a “true” no-load

feature. If both the active and reactive energy fall below the

no-load threshold, there is no resistive, inductive, or capacitive

load. The active energy no-load feature can also be used to

prevent creep of the active energy when there is an inductive

or capacitive load present.

If the active energy on either Current Channel A (phase)

or Current Channel B (neutral) falls below the programmed

threshold, the active energy on that channel ceases to accumu-

late in the AENERGYA and AENERGYB registers, respectively.

If either the CF1 or CF2 pin is programmed to output active

energy, the CF output is disabled and held high (see the Energy-

to-Frequency Conversion section). If enabled, the active reverse

power indication (REVP) holds its current state while in the no-

load condition (see the

section). The Current

Channel A active energy no-load condition is indicated by the

AP_NOLOADA bit (Bit 6) in the IRQSTATA register (Address

0x22D and Address 0x32D). The Current Channel B active energy

no-load condition is indicated by the AP_NOLOADB bit (Bit 6)

in the IRQSTATB register (Address 0x230 and Address 0x330).

Reverse Power

Current Channel A and Current Channel B are independent

and, therefore, a no-load condition on Current Channel A

affects only the energy accumulation, CF output, and reverse

power of Current Channel A, and vice versa.

The active energy no-load feature is enabled by default and can

be disabled by setting Bit 0 in the DISNOLOAD register

(Address 0x001) to 1.

Active Energy No-Load Interrupt

Two interrupts are associated with the active energy no-load

feature: one for Current Channel A (phase) and one for Current

Channel B (neutral). If enabled, these interrupts are triggered

when the active energy falls below the programmed threshold.

The Current Channel A active energy no-load interrupt can be

enabled by setting the AP_NOLOADA bit (Bit 6) in the IRQENA

an active energy no-load event on Current Channel A causes

the IRQ pin (Pin 22) to fall to 0 (see the

section).

Primary Interrupts

(Voltage Channel and Current Channel A)

The Current Channel B active energy no-load interrupt can be

enabled by setting the AP_NOLOADB bit (Bit 6) in the IRQENB

an active energy no-load event on Current Channel B triggers

the IRQ alternative output (see the

section).

Current Channel B Interrupts

ADE7953 数据表(PDF) 40 Page - Analog Devices

ADE7953 数据表(HTML) 40 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

数据表下载