SA2005P_技术文档

Programmable Three Phase Power / Energy Metering

IC for Stepper Motor / Impulse Counter Applications

SA2005P

ssames

FEATURES

+

Meets the IEC 521/1036 Specification requirements for

Class 1 AC Watt hour meters

+

Direct drive for electro-mechanical counters or stepper

motors

Calibration and setup stored on external EEPROM - no

trim-potsrequired

+

Operates over a wide temperature range

Easily adaptable to different signal levels

Adaptable to different types of sensors

Precision voltage reference on-chip

Protected against ESD

Flexible programmable features providing ease of

implementationformetermanufacturers

Perphaseenergydirectionandvoltagefailindication

Precisionoscillatoronchip

+

DESCRIPTION

A programmable rate pulse output is available for meter

calibration purposes. Per phase voltage fail and voltage

sequence faults as well as energy direction indication are

available as LED outputs. Programmable dividers enable

various mechanical counter or stepper motor counter

resolutions.

The SAMES SA2005P provides a single chip active energy

metering solution for three phase mechanical counter-based

meter designs.

Th SA2005P does not require any external trim-pots or resistor

ladders for meter calibration. Calibration and meter

configuration information is stored on a small external

EEPROM.

A precision oscillator, that replaces an external crystal, is

integratedonchip. Avoltagereferenceisintegratedonchip.

Meter setup stored on the EEPROM includes various metering

direction modes (total sum, absolute sum, positive or negative

energy) phase calibration data, rated metering conditions,

LED pulse rate, counter pulse width, counter resolution and

creep current.

The SA2005P integrated circuit is available in 24-pin dual in

line plastic (DIP-24) and small outline (SOIC-24) package

options.

VDD VSS

IIN1

IIP1

I1

CHANNEL

BALANCE

LED

X

IVN1

V1

MON

POWER

MOP

PROGRAM-

IIN2

IIP2

I2

PROG.

CHANNEL

TO

PH / DIR

MABLE

PULSE

IVN2

ADDER

BALANCE

V2

PH1

ADDER

RATE

IIN3

IIP3

I3

PH2

CHANNEL

BALANCE

PH3

IVN3

V3

GND

RLOAD

INTERFACE

REF

TIMING & CONTROL OSC

dr-01605

VREF

SDA

SCL

TEST

Figure 1: Block diagram

1/16

SPEC-0086 (REV. 2)

07-02-01

SA2005P

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ELECTRICAL CHARACTERISTICS

#

(V = 2.5V, V = -2.5V, over the temperature range -10°C to +70°C , unless otherwise specified.)

SS

DD

Symbol

Typ

Parameter

Min

Max

Unit

Condition

Operating temp. Range

T

-25

+85

2.75

-2.25

16

°C

V

O

V

DD

Supply Voltage: Positive

Supply Voltage: Negative

Supply Current: Positive

2.25

-2.75

V

SS

V

I

DD

15

mA

I

SS

16

Supply Current: Negative

Current Sensor Inputs (Differential)

I

II

µA

Input Current Range

-25

+25

Peak value

Voltage Sensor Input (Asymmetrical)

I

IV

µA

-25

+25

Peak value

Input Current Range

With R = 24kW

Pin VREF

µA

V

-I

45

50

55

R

connected to V

Ref. Current

Ref. Voltage

SS

1.1

V

1.3

R

Reference to V

SS

Digital I/O

Pins RLOAD, TEST, SDA

Input High Voltage

V

V -1

DD

IH

V

V +1

SS

IL

Input Low Voltage

Pins MOP, MON, LED, SCL,

PH/DIR, PH1, PH2, PH3

Output High Voltage

V -1

DD

V

I

= -2mA

V

OH

I

OL

= 5mA

V +1

SS

Output Low Voltage

OL

Pin SDA

V = V

I

-I

IL

SS

24

54

µA

Pull up current

Pins TEST, RLOAD

Pull down current

V = V

I

IH

DD

48

110

µA

#Extended Operating Temperature Range available on request.

ABSOLUTEMAXIMUMRATINGS*

Parameter

Symbol

Min

Max

6.0

Unit

V

mA

°C

Supply Voltage

V -V

DD

-0.3

-150

-40

SS

Currentonanypin

StorageTemperature

OperatingTemperature

I

+150

+125

+85

T

STG

T

O

-40

°C

*Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress

rating only. Functional operation of the device at these or any other condition above those indicated in the operational sections of

this specification, is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect device reliability.

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SA2005P

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PIN DESCRIPTION

Designation

Description

Analog Ground. The voltage to this pin should be mid-way between V and V .

SS

20

6

GND

DD

V

DD

Positive supply voltage. Typically +5V if a current transformer is used for current sensing.

V

SS

Negative supply voltage. Typically 0V if a current transformer is used for current sensing.

18

Voltage sense inputs. The current into the A/D converter should be set at 14µA at nominal mains

RMS

21, 24, IVN1, IVN2,

voltage. The voltage sense input saturates at an input current of ±25µA peak.

3

IVN3

Inputs for current sensors. The termination resistor voltage from each current transformer is

23, 22,

2, 1,

IIN1, IIP1,

IIN2, IIP2,

IIN3, IIP3

converted to a current of 16µA at rated conditions. The current sense input saturates at an input

RMS

current of ±25µA peak.

5, 4

19

This pin provides the connection for the reference current setting resistor. A 24kW resistor

VREF

connected to V sets the optimum operating condition.

SS

8

SCL

Serial clock output. This output is used to strobe data from the external EEPROM.

SDA

9

Serial data. Send and receive data from an external EEPROM.

Test input. For normal operation connect this pin to V .

SS

17

TEST

Calibration LED output. Refer to section Led Output (LED) for the pulse rate output options.

LED

10

Motor pulse outputs. These outputs can be used to drive an impulse counter or stepper motor directly.

11, 12 MON, MOP

PH / DIR

13

Multiplexed phase or direction driver output.

Triggers a data reload from the external EEPROM.

7

RLOAD

14, 15, PH1, PH2,

Multiplexed LED drivers for direction and mains fail indication.

16

PH3

ORDERING INFORMATION

IIP2

1

24 IVN2

Part Number

SA2005PPA

SA2005PSA

Package

DIP-24

IIN2

IIN1

2

23

IVN3

IIP3

3

22 IIP1

SOIC-24

IVN1

21

4

IIN3

VDD

GND

5

20

19

18

17

16

15

14

13

VREF

6

RLOAD

VSS

7

SCL

TEST

8

PH3

SDA

9

LED

PH2

10

11

12

MON

MOP

PH1

PH / DIR

dr-01602

Figure 2: Pin connections: Package: DIP-24, SOIC-24

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SA2005P

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FUNCTIONAL DESCRIPTION

The SAMES SA2005P is a CMOS mixed signal analog/digital

integrated circuit that performs three phase power/energy

calculations across a power range of 1000:1 to an overall

accuracy of better than Class 1.

operation of the meter. Every data byte stored in the EEPROM

is protected with a checksum byte to ensure data integrity.

ELECTROSTATIC DISCHARGE (ESD) PROTECTION

The SA2005P integrated circuit's inputs/outputs are protected

against ESD.

The integrated circuit includes all the required functions for 3-

phase power and energy measurement such as oversampling

A/D converters for the voltage and current sense inputs, power

calculation and energy integration. Internal offsets are

eliminated through the use of cancellation procedures.

POWER CONSUMPTION

The overall power consumption rating of the SA2005P

integrated circuit is less than 80mW with a 5V supply.

The integrated circuit includes all the required functions for a

three phase mechanical counter-based meter design. A

precision oscillator, that replaces an external crystal, is

integrated on chip providing a temperature stable time base for

the digital circuitry. A temperature stable voltage reference

integrated on chip generates the reference current used by the

analog circuitry.

INPUT SIGNALS

ANALOG INPUT CONFIGURATION

The current and voltage sensor inputs are illustrated in figure 3.

These inputs are protected against electrostatic discharge

through clamping diodes, in conjunction with the amplifiers

input configuration. The feedback loops from the outputs of the

amplifiers A and A generate virtual shorts on the signal inputs.

I

V

Exact duplications of the input currents are generated for the

analog processing circuitry. The current and voltage sense

inputs are identical. Both inputs are differential current driven

up to ±25µA peak. One of the voltage sense amplifiers input

terminals is internally connected to GND. This configuration is

possible because the voltage sense input is much less

sensitive to externally induced parasitic signals compared to

the current sense inputs.

Voltage and currents are sampled simultaneously by means of

a sigma delta modulator type ADC and power is calculated for

each individual phase. A programmable channel balance on

each channel is used for individual channel calibration.

The scaled power is fed to a programmable adder that allows

the representation of the measured energy to be either total

sum or absolute sum.

Current Sense Inputs (IIN1, IIP1, IIN2, IIP2, IIN3, IIP3)

The current sense inputs connects to a termination resistor

connected across the terminals of a current transformer. At

The summed power is integrated and divided down to

represent integrated energy. Pulses on the LED output and on

the mechanical counter outputs represent measured amounts

of energy. The programmable dividers provide flexible counter

and calibration LED resolutions.

V

DD

IIP

Outputs for phase voltage fail and voltage sequence faults and

energy direction are available.

V

SS

CURRENT

SENSOR

INPUTS

A_I

V

DD

The SA2005P does not require any external trim-pots or

resistor ladders as meter calibration and configuration data is

stored on a small external EEPROM. The SA2005P configures

itself from the EEPROM during power up. These features

enables meter manufacturers flexible meter designs from a

single integrated circuit.

IIN

V

SS

V

DD

IVP

AUTOMATIC DEVICE CONFIGURATION (BOOT UP)

During power up, registers containing configuration and

calibration information is updated from an external EEPROM.

The device itself never writes tot he EEPROM so any write

protect features offered by manufacturer of EEPROM’s may

be used to protect the configuration and calibration constant of

the meter. The device reloads its configuration every 1193

seconds from the external EEPROM in order to ensure correct

VOLTAGE

SENSOR

INPUT

V

SS

A

V

GND

DR-01288

Figure 3: Analog input internal configuration

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SA2005P

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Reload(RLOAD)

rated current the resistor values should be selected for input

A falling edge on the RLOAD pin will trigger a register update

from the external EEPROM. This feature may be used during

calibration to load updated register data in the SA2005P. For

normal operation of the SA2005P the RLOAD pin may be left

floating.

currents of 16µA . Referring to figure 8, the resistors R1 and

RMS

R2 on current channel 1, resistors R3 and R4 on current

channel 2 and resistors R5 and R6 on current channel 3, define

the current level into the current sense inputs of the SA2005P.

The current sense inputs saturates at an input current of

±25µA peak. Resistors R29, R30 and R31 are used as current

transformer termination resistors. The voltage drop across the

termination resistors should be at least 20mV at rated

conditions. Values for the current sense inputs are calculated

as follows:

Test Inputs (TEST)

The TEST input is the manufacturers test pin and must be

connectedtoVSSinameteringapplication.

OUTPUT SIGNALS

LEDOutput(LED)

R

1

3

5

= R

2

4

6

= ( I

L

/ 16µARMS ) x R29 / 2

/ 16µARMS ) x R30 / 2

/ 16µARMS ) x R31 / 2

Four options for the LED output pulse rate are available, 6400,

3200, 1600 pulses per kWh, and a pulse rate of 1252 pulses

per second at rated conditions. At 1252 pulses per second t LED

is 71µs, for the other options tLED is 10ms. The LED output is

activelowasshowninfigure4.

Where:

I = Line current/CT-ratio

L

In case a current transformer is used for current sensing the

value of the termination resistors should be less than the

resistance of the CT's secondary winding.

VDD

LED

VSS

Voltage Sense Inputs (IVN1, IVN2, IVN3)

DR-01332

t

LED

The mains voltage are measured by means of a resistor divider

and the divided voltage are converted to a current. The current

into the voltage sense inputs (virtual ground) should be set to

14µARMS at rated voltage conditions. The individual mains

Figure 4: LED pulse output

Motor Output (MOP, MON)

The motor pulse width is programmable for 71ms, 142ms and

284ms. The MON pulse will follow the MOP pulse within the

selected pulse width time. This prevents the motor armature

being in the wrong position after a power failure. Both MOP

and MON outputs are active high. A MOP pulse followed by a

MON pulse represents one energy pulse. The motor drive

waveforms are shown in figure 5.

voltages are divided down to 14V per phase. The resistors

RMS

R12, R13 and R14 (figure 8) set the current for the voltage

sense inputs. The voltage sense inputs saturate at an input

current of ±25uA peak.

Voltage Reference Connection (VREF)

A bias resistor of 24k provides an optimum bias conditions on

chip. Calibration of the SA2005P is done by means of divider

ratios stored on an external EEPROM. This is described in the

Device Configuration section.

VDD

MOP

VSS

Serial Data (SDA)

VDD

The SDA pin connects directly to the SDA pin of an external

EEPROM. The pin is used to transfer data between the

EEPROM and the SA2005P. An external pull-up resistor in not

needed.

MON

VSS

DR-01559

t_m

Figure 5: Motor drive on MON and MOP pins of device

Serial Clock (SCL)

Multiplex Output (PH/ DIR)

The SCL pin connects directly to the SCL of an external

EEPROM. The SCL output is used to strobe data at a rate of

50kHz out of the EEPROM. An external pull up resistor is not

needed. The SCL output uses a soft driver and may be

overdriven by the calibration equipment.

The PH/DIR output enables either direction or voltage

information on the phase LED driver outputs (PH1, PH2 and

PH3). This multiplex output switches between logic 1 and 0 at

a frequency of approximately 280Hz. A logic 1 enables energy

direction information on the LED driver outputs and a logic 0

enables voltage information.

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inputs are out of phase (greater than 90 degrees). Positive

energy flow is defined as the condition where the voltage

sense and current sense inputs are in phase.

The PH/Dir output is used in conjunction with the LED driver

outputs to display information about each individual phase, see

figure 6.

PH/DIR = 0 (Voltage fail / phase sequence error)

Phase LED Drivers (PH1, PH2, PH3)

When PH/DIR is low (logic 0) voltage information is available

on PH1, PH2 and PH3. A logic 0 on any of these pins indicates

a voltage failure, the SA2005P does not detect a zero crossing

on the applicable voltage sense input. Referring to figure 6 the

voltage fail LED will be on when the voltage phase is present

and off when the voltage phase is missing.

The LED driver outputs present either direction information or

voltage information. The three LED driver outputs are used in

conjunction with the PH/DIR output to display information

about each individual phase (refer to figure 6) as follows:

PH/DIR = 1 (Direction indication)

When PH/DIR is high (logic 1) energy direction information for

each individual phase is available on PH1, PH2 and PH3. A

logic 0 indicates reverse energy flow and a logic 1 indicates

positive energy flow. Reverse energy flow is defined as the

condition where the voltage sense input and the current sense

In the case of a phase sequence error all three LED driver

outputs PH1, PH2 and PH3 will pulse with a repetition rate of

approximately 1Hz.

PH (Sink)

DIR (Drive)

PH/DIR

D1

D2

D3

D4

D5

D6

VFAIL 1

R9

DIR1

VFAIL1

DIR2

VFAIL2

DIR3

VFAIL3

Channel 1

DIR 1

PH1

VFAIL 2

R10

Channel 2

DIR 2

PH2

VFAIL 3

R11

Channel 3

DIR 3

dr-01603

PH3

Figure 6: Multiplexing of the LED Drivers

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ANTI-TAMPER CONDITIONS

The SA2005P cater for the following meter tamper conditions and are indicated as follows:

Description

Method

Result

One LED is provided for each phase to indicate abnormal

operating conditions.

During normal conditions, the LEDs

are continuously switched on.

Phase

Voltages

Phase Failure,

no voltage

The SA2005P will record the energy

In case of a phase failure, the corresponding LED is

switched off.

consumption accurately under this condition

Phase

In case of phase sequence error, all LEDs are flashing with a re-

petition rate of approximately 1 Hz. A connection of a line voltage

to the neutral terminal would be indicated in the same way.

The SA2005P will record the energy

Sequence

Error

consumption accurately under this condition

One LED is provided for each current sensor to indicate reverse

energy flow. If detected, the corresponding LED is switched on.

The SA2005P can be configured to accumulate the absolute

energy consumption for each phase measured, irrespective of

the direction of the energy flow.

Input / Output

Terminals

The SA2005P will record the energy

consumption accurately under this condition

Interchanged

Missing

The architecture of the meter should provide for a good "phantom

neutral" in cases where the neutral is disconnected from the

meter.

In this case, the meter would register the

energy consumption correct.

Neutral

Connection

Return

The SA2005P will therefore record the energy consumption

A indication for this condition could be

realized external to the IC.

through Earth accurately under this condition.

The SA2005P will record the energy

consumption accurately under this condition

The meter can not be re-adjusted, only

reprogrammed.

Load

Imbalance

The calibration data is stored in an EEPROM. There are no

trim-pots required in this design.

Calibration

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SA2005P

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DEVICE CONFIGURATION

Power from S - D converters

641454 pulses/s

SIGNAL FLOW DESCRIPTION

The following is an overview of the SA2005P’s registers. For a

detailed description of each parameter please refer to

parameter description section. Figure 7 shows the various

registers in the SA2005P’s power to pulse rate block. The

inputs to this block are three single bit pulse density modulated

signals, each having a pulse rate of 641454 pulses per second

at rated conditions. The parameters Cb1, Cb2, Cb3, Sum, Ct,

Kr, CresH, CresL, Cled and Pw contain values that are read

from the external EEPROM during power up.

Pre-Divider

÷Cb1

Pre-Divider

÷Cb2

Pre-Divider

÷Cb3

Programmable Adder SUM

Creep current threshold detector

Ct

The Pre-Divider registers are used for calibration and to

balance the gain of each channel. TheProgrammable Adder is

used to select between the total sum or absolute sum of the

measured energy. The Creep current threshold detector

selects the creep current which is relative to the meters rated

current. The Rated Condition register is used to program the

rated condition of the meter and feeds the registers LED-

constant and Counter Resolution with the applicable pulse

rate. These two registers are programmed to select the LED

output rate and the counter resolution (pulses per kWh)

respectively. The Counter Pulse Width register is used to

program the pulse width for the mechanical counter driver

output MOP and MON.

Normally 1253p/s

Rated Condition

÷Kr

Normally 6400p/kWh

Counter

Resolution

CresH, CresL

LED-Constant

Cled

Counter Pulse

width

Pw

MOP

MON

LED

Figure 7: Signal flow block diagram

EEPROM Memory Allocation

contains a XORed byte of the previous even byte. This is the

checksum byte used by the SA2005P to ensure data integrity.

The following table shows the EEPROM memory allocation as

well as the corresponding name. The uneven byte always

2

Description

E Address

Bit [7:0]

Contents

Cb3

XOR of ADDR 10

Cb1

XOR of ADDR 12

Cb2

XOR of ADDR 14

SUM

Name

Channel Balance 3

10

---v vvvv

xxxx xxxx

---v vvvv

xxxx xxxx

---v vvvv

xxxx xxxx

---- --vv

v--- ----

xxxx xxxx

vvvv vvvv

xxxx xxxx

---- --vv

xxxx xxxx

vvvv vvvv

xxxx xxxx

---v vvvv

vv-- ----

xxxx xxxx

D10

11

Channel Balance 1

12

13

14

15

16

17

20

21

22

23

24

25

26

27

D12

Channel Balance 2

D13

D16

Summing mode

Creep current threshold

Ct

XOR of ADDR 16

Kr

XOR of ADDR 20

Cled

XOR of ADDR 22

CresL

XOR of ADDR 24

ClresH

Rated Condition

D20

D22

D24

Led Pulse-rate

Counter Resolution (LSB)

D26

Counter Resolution (MSB)

Counter Pulse-Width

Pw

XOR of ADDR 26

KEY: (- = DON’T CARE); (V = VALUE/PARAMETER); (0,1 = LOGICAL VALUE); (X = BIT-XOR)

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PARAMETER DESCRIPTION

LED Pulse-Rate (Cled)

Refer to the EEPROM memory allocation map as well as the

Signal flow diagram figure 7, for a description of the registers

used in this section.

Two bits of byte D22 allow for the selection of 4 different LED-

Pulse-rates. The LED pulse-width is 10ms. In fast pulse mode,

the pulse-width is set to 71µs.

D22[1]

D22[0] Calibration LED - Output

Rated Condition (Kr)

Kr is used to program the rated condition of the meter. Rated

conditions from less than 10A to several 100A are possible.

The rated conditions divider as well as the pre-divider is used

to compensate for individual phase calibration. The three

phases are calibrated to the phase with the lowest gain.

0

1

0

1

0

1

0

6400 p/kWh

3200 p/kWh

1600 p/kWh

1252 pulses/second @ rated for

fast calibration

Kr is calculated as follows:

Counter Resolution (Cres)

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

A 13 bit divider divide the pulse rate from the rated conditions

divider down to the desired counter resolution.

The SA2005P’s internal counters count from 0 so 1 must be

subtracted from Kr:

Cres is made up of bits 0 of 4 of byte D26 and byte D27.

Kr = round(Krx)-1

D26[4:0] D27[7:0] Counter Resolution

Where:

Counter Pulse-Width (Pw)

Krx is the real value

Kr is the integer value

Kr is made up of 1 byte (D20)

The pulse width for the mechanical counter driver output is

selectable to accommodate various step-motor and impulse-

counter requirements.

Pre-divider (Cb1, Cb2, Cb3)

Pw is made up of bits 7 and 6 of byte D26.

The channel balance (Cb) value is used to balance the three

phases. The rated conditions divider ratio must be calculated.

Error measurements per phase are done with channel balance

values set to zero. The measured error values are used to

correct the error measurements of the three phases. The

rounding error in the rated conditions divider is also

compensated for in the channel balance calculations. One

count on the channel balance value represent 100%/256.

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

D26[7]

D26[6] Counter Pulse-Width

1

0

-

284 ms

142 ms

71 ms

1

0

Creep current threshold (Ct)

The creep current is expressed relative to the rated current of

the meter. The SA2005P will not meter currents below the

creep current. The creep current is implemented to prevent

the meter from accumulating energy when no load is

connected.

Gain calculates the rounding error made by the rated

conditions divider.

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

Cb2 = (CHB2 - CBMIN + Gain) x 256 / 100

Cb3 = (CHB3 - CBMIN + Gain) x 256 / 100

Cs is made up of bit 7 of byte D16

D16[7]

Creep threshold

CHB1, CHB2, CHB3 is the measured channel balance %error

that will be corrected

0

1

0.02% of rated current

0.01% of rated current

CBMIN is the lowest channel balance %error measured

between the three phases.

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Programmable adder mode (SUM)

The SA2005P can be programmed to sum the energy

measurement as follows:

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:

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.

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

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

Gain = 0.8679

Energy = Energy phase 1 + Energy Phase 2 + Energy

Phase 3

The real channel balance errors still need to be measured so

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

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.

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

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.

Convert to integer

Cb1 = 2

D16[2] D16[1] D16[0] Counter Resolution

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.

0

1

0

1

0

1

0

1

0

1

0

1

0

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

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.

Example of calculating rated conditions and channel

balance values

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

values)

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

Calculate the rated conditions:

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;

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).

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Recalculate the rated conditions

Krx = 642 000 / Rated volt / Rated current / 6400 x 3600 x

1000 / 512 x (1 + %MinError / 100 )

Krx = 642 000 / 230 / 80 / 6400 x 3600 x 1000 / 512 x 1.015

Krx = 38.9077

Kr = 38 - 1 = 37

The 37 are stored in the rated register.

The channel balance values are adjusted to make provision for

the rounding error.

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

Gain = (( 38.9077 - 38 ) / 38.9077 ) x 100

Gain = 2.33

The channel balance pre-devider value must be recalculated.

(BMIN will be the lowest %error value, in this case 1.5%,

CHB1, CHB2 and CHB3 are the individual phase %errors

measured.

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

Cb1 = (1.5 - 1.5 + 2.33 ) x 256 / 100 = 5.97 =5

Cb2 = (CHB2 - CBMIN + Gain ) x 256 / 100

Cb2 = ( 5.2 - 1.5 + 2.33 ) x 256 / 100 = 15.43 = 15

Cb3 = (CHB3 - CBMIN + Gain ) x 256 / 100

Cb3 = (3.2 - 1.5 + 2.33 ) x 256 / 100 = 10.316 = 10

Store the calculated values in the EEPROM and the meter is

calibrated.

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TYPICAL APPLICATION

CALCULATION OF EXTERNAL RESISTOR VALUES

In figure 8, all the components required for a three-phase

power/energy metering section, is shown. The application

uses current transformers for current sensing. The 4-wire

meter section is capable of measuring 3x230V/80A with

precision better than Class 1

VoltageDivider

The three voltage divider for voltage measurement are

identical so resistor values for one phase will be calculated.

The voltage divider is calculated for a voltage drop of 14V.

Equationsforthevoltagedividerinfigure5are:

RA = R16 + R19 + R22

RB = R8 || R13

The most important external components for the SA2005P

integrated circuit are the current sense resistors, the voltage

sense resistors as well as the bias setting resistor.

Combiningthetwoequationsgives:

Bias Resistor

(RA + RB ) / 230V = RB / 14V

Resistor values R11 = R12 = R13= 24kW and R8 =1MW is

chosen.

R7 defines all on-chip and reference currents. With R7=24kW,

optimum conditions are set.

CT Termination Resistor

Substitutingthevaluesresultin:

The voltage drop across the CT termination resistor at rated

current should be at least 20mV. The CT's used have low

phase shift and a ratio of 1:2500.The CT is terminated with a

2.7W resistor giving a voltage drop across the termination

resistor 864mV at rated conditions (Imax for the meter).

RB = 23.4375kW

RA = RB x (230V / 14V - 1)

RA = 361.607kW.

Resistor values of R16, R19 and R22 is chosen to be 130k,

130kand100k.

Current Sense Resistors

The resistors R1 and R2 define the current level into the

current sense inputs of phase one of the device. The resistor

values are selected for an input current of 16µA on the current

inputs at rated conditions.

The three voltage channels are identical so R14= R15= R16 ,

R17=R18=R19andR20=R21=R22.

According to equation described in the Current Sense inputs

section:

R1 = R2 = ( I / 16µA ) x R / 2

SH

L

= 80A /2500 / 16µA x 2.7W / 2

= 2.7kW

I =Linecurrent/CTRatio

L

The three current channels are identical so R1 = R2 = R3 = R4

=R5=R6.

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Parts List for Application Circuit: Figure 7

Symbol

U1

Description

Detail

SA2005P

DIP-24 / SOIC-24

Resistor, 2.7k, 1/4W, 1%, metal

Resistor, 24k, 1/4W, 1%, metal

Resistor, 1k, 1/4W, 5%, carbon

Resistor, 1M, 1/4W, 1%, metal

Resistor, 24k, 1/4W, 1%, metal

Resistor, 130k, 1/4W, 1%, metal

Resistor, 100k, 1/4W, 1%, metal

Resistor, 1k, 1/4W, 1%, metal

Resistor, 2.7W, 1/4W, 1%, metal

Capacitor, 220nF

Note 1

R1

R2

R3

R4

R5

R6

R7

R8

R9

R10

R11

R12

R13

R14

R15

R16

R17

R18

R19

R20

R21

R22

R23

R24

R25

R26

R27

R28

R29

R30

R31

C1

Note 1

Capacitor, 220nF

C2

Capacitor, 1.5µF, 16V, electrolytic

Capacitor, 820nF

Note 2

C3

Note 2

C4

Note 2

C5

Note 3

C6

3mm Light emitting diode

Direction indicator

V1 Fail indicator

Direction indicator

V2 Fail indicator

Direction indicator

V3 Fail indicator

D1

3mm Light emitting diode

D2

3mm Light emitting diode

D3

3mm Light emitting diode

D4

3mm Light emitting diode

D5

3mm Light emitting diode

D6

24C01A, 1kbit EEPROM

U2

Mechanical stepper motor counter

Current Transformer, TZ76

CNT1

CT1

CT2

CT3

2500:1

Note 1: Resistor (R1 to R6) values are dependent on the selection of the termination resistors (R29 to R31) and CT combination

Note 2: Capacitor values may be selected to compensate for phase errors caused by the current transformers.

Note 3: Capacitor C6 to be positioned as close as possible to supply pins V and V of U1 as possible.

DD

SS

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DISCLAIMER:

The information contained in this document is confidential and proprietary to South African Micro-Electronic Systems (Pty) Ltd

("SAMES") and may not be copied or disclosed to a third party, in whole or in part, without the express written consent of SAMES.

The information contained herein is current as of the date of publication; however, delivery of this document shall not under any

circumstances create any implication that the information contained herein is correct as of any time subsequent to such date.

SAMES does not undertake to inform any recipient of this document of any changes in the information contained herein, and

SAMES expressly reserves the right to make changes in such information, without notification, even if such changes would render

information contained herein inaccurate or incomplete. SAMES makes no representation or warranty that any circuit designed by

reference to the information contained herein, will function without errors and as intended by the designer.

Any sales or technical questions may be posted to our e-mail address below:

energy@sames.co.za

For the latest updates on datasheets, please visit our web site:

http://www.sames.co.za.

SOUTH AFRICAN MICRO-ELECTRONIC SYSTEMS

DIVISION OF LABAT TECHNOLOGIES (PTY) LTD

Tel: (012) 333-6021

Tel: Int +27 12 333-6021

Fax: (012) 333-8071

Fax: Int +27 12 333-8071

33 ELAND STREET

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PRETORIA

P O BOX 15888

33 ELAND STREET

LYNN EAST 0039

REPUBLIC OF SOUTH AFRICA

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型号：	SA2005P
厂家：	SAMES
描述：	Programmable Three Phase Power / Energy Metering IC for Stepper Motor / Impulse Counter Applications 可编程的三相功率/电能计量芯片的步进电机/脉冲计数器的应用计数器脉冲电机
文件：	总16页 (文件大小：197K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

SA2005P [SAMES]

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