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THREE PHASE POWER/ENERGY METERING MODULE

PULSE OUTPUT

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4310

PDS038-SA9105-001

Rev. B

13-09-95

FEATURES

Performs one, two or three phase power
and energy measurement

Meets the accuracy requirements for
Class 1 AC Watt hour meters

Operates over a wide Temperature
Range

Uses current transformers for current
sensing

Three pulse rate outputs available

Protected agianst ESD

SA9105 APPLICATION NOTE

PM9105AF

DESCRIPTION

The SAMES three phase power/energy metering module, the PM9105AF provides three
pulse rate output options, the frequency of which are proportional to the active power
consumption.

Energy consumption can be determined by the power measurement being integrated
over time.

The method of calculation takes the power factor into account.

The output of this innovative universal three phase power/energy metering circuit is
ideally suited for energy calculations in applications using a µ-controller or mechanical
counter.

The application utilises the SAMES SA9105AF, SA9105EF or SA9105FF three phase
power metering integrated circuits for power measurement.

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BLOCK DIAGRAM

ABSOLUTE MAXIMUM RATINGS *

Parameter

Symbol

Min

Max

Unit

Supply Voltage (Note 1)

540

Storage Temperature

STG

-25

+125

°C

Operating Temperature (Note 2)

-10

+70

°C

Note 1:

Voltages are specified with reference to Neutral.

Note 2:

The SA9105 integrated circuit is specified to operate over the temperature
range -10°C to +70°C. The module functionality will however depend upon
the external components used.

* 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 conditions above those indicated in the operation sections of this
specification, is not implied. Exposure to Absolute Maximum Ratings for extended
periods may affect device reliability.

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ELECTRICAL CHARACTERISTICS
(Over the temperature range -10°C to +70°C, unless otherwise specified. Power
consumption figures are applicable to the PM9105AFE only.)

Parameter

Symbol

Min Typ

Max Unit

Condition

Supply Voltage (x3 Phases)

180

230

265

PM9105AFE

(Continuous)

115

138

PM9105AFA

Frequency Output

FOUTX

Refer to applicable IC data sheet

Power Consumption

100

= 5V

Note 1:

Power consumption specifications exclude power consumed by the current
sensors.

CONNECTION DESCRIPTION

Designation

Description

PL5

Voltage Supply connected to Phase 1
Voltage Supply connected to Phase 2
Voltage Supply connected to Phase 3
Voltage Supply connected to Neutral Line (Common)

PL6

Power Output: 4Hz at rated current
Power Output: 290 Hz at rated current
Power Output: 1160 Hz at rated current
0V (Common)

PL4

5V DC Supply Voltage
0V DC Supply Voltage

CT1

Phase 1 (Direction indicated on PCB)

CT2

Phase 2 (Direction indicated on PCB)

CT3

Phase 3 (Direction indicated on PCB)

FUNCTIONAL DESCRIPTION

Power Calculation
In the Application Circuit (see Figure 2), the output currents from the current sensors
will be between 0 and 16µA. The current input stages saturate at input currents
greater than 18µA

RMS

. The mains voltage (mains voltage + 15% - 20%) is used for

the power calculation, together with the current information from the current sensors
(current transformers).

The calculated power for the 3 phases is integrated over time and converted into a
corresponding frequency.

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For rated conditions, the signals into the current and voltage sensor inputs are set
as follows:

Current sensor input currents:

16µ A

RMS

Voltage sensor input currents:

14µ A

RMS

Under these conditions, the device generates a pulse rate of 1,16kHz at output
FOUT1.

The output frequency at FOUT2 is FOUT1/4. At FOUT3 the output frequency is
FOUT1/290.

Electrostatic Discharge (ESD) Protection
The device's inputs/outputs are protected against ESD according to Mil-Std 883C,
method 3015. The modules resistance to transients will be dependant upon the
protection components used.

Power Consumption
The overall power consumption rating for this power metering application (Figure 2),
is under 500mW, excluding the current sensors.

Isolation
The reference for the unit is connected to neutral.

Circuit Description
The module is supplied from an external 5V DC supply.

The Application Circuit (figure 2), details the components required for a three phase
power metering module. Terminated current transformers are used as current
sensors.

The most important external components are:

, C

and C

are the outer loop capacitors for the integrated oversampling

A/D converters. The typical value of C

is 2.2nF and the value of C

, C

and C

560pF.

The actual values determine the signal to noise and stability performance. The
tolerances should be within ± 10%.

, C

and C

are the inner loop capacitors for the integrated oversampling

A/D converters. The typical value of C

, C

and C

is 3.3nF. Values smaller than

0.5nF and larger than 5nF should be avoided.

Terminated current sensors (current transformers) are connected to the current
sensor inputs of the SA9105 through current setting resistors (R

..R

The resistor values should be selected for an input current of 16

A into the SA9105

at the rated line current.

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The values of these resistors should be calculated as follows:

Phase 1:

= R

= (I

/16

A) x R

Phase 2:

= R

= (I

/16

A) x R

Phase 3:

= R

= (I

/16

A) x R

Where I

Secondary CT current at rated conditions.

, R

and R

Termination resistors of the three current transformers.

+ R

, R

and R

set the current for the phase 1 voltage sense input. R

+ R

+ P

and R

set the current for phase 2 and R

+ R

, R

+ P

and R

set the current

for Phase 3. The values should be selected so that the input currents into the voltage
sense inputs (virtual ground) is set to 14

A at nominal line voltage. Capacitors C1,

C2 and C3 are for decoupling and phase compensation.

+ P

defines all on-chip bias and reference currents. With R

+ P

= 24k

optimum conditions are set. P

may be varied within ± 10% for calibration purposes.

Any changes to R

will affect the output quadratically (i.e:

R = +5%,

FOUT =

+10%).

XTAL is a colour burst TV crystal (f = 3.5795 MHz) for the oscillator. The oscillator
frequency is divided down to 1.7897 MHz on-chip to supply the digital circuitry and
the A/D converters.

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Figure 2: Application for Three Phase Power/Energy Measurement.

SA9105

PLCC-44

IC-1

R11

CT2

2 . 5 V

CT3

5 V

0 V

2 . 5 V

R20

DR-00882

X T A L

C12

R13

R12

CT1

R19

R18

0 V

M A I N S V O L T A G E S

PH1

PH2

PH3

R10

R 3 A

R 2 A

R 1 A

C11

C14

P14

O V

R14

0 V

FOUT3

FOUT2

FOUT1

C13

5 V

0 V

R17

R16

R15

C10

R21

2 . 5 V

5 V

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Parts List for Application Circuit: Figure 2

Item

Symbol

Description

Detail

IC-1

SA9105AF/SA9105EF

PLCC-44

XTAL

Crystal, 3.5795 MHz

TV Crystal

Resistor, 1%, ¼W, Metal

Note 4

R1A

Resistor, 1%, ¼W, Metal

Note 4

Resistor, 1%, ¼W, Metal

Note 4

R2A

Resistor, 1%, ¼W, Metal

Note 4

Resistor, 1%, ¼W, Metal

Note 4

R3A

Resistor, 1%, ¼W, Metal

Note 4

Resistor, 24k, 1%, ¼W, Metal

Resistor, 22k, 1%, ¼W, Metal

Resistor, 820

, 1%, ¼W, Metal

Resistor, 2.7k, 1%, ¼W, Metal

Note 1

Resistor, 2.7k, 1%, ¼W, Metal

Note 1

R10

Resistor, 2.7k, 1%, ¼W, Metal

Note 1

R11

Resistor, 2.7k, 1%, ¼W, Metal

Note 1

R12

Resistor, 2.7k, 1%, ¼W, Metal

Note 1

R13

Resistor, 2.7k, 1%, ¼W, Metal

Note 1

R14

Resistor, 22k, 1%, ¼W, Metal

R15

Resistor, 1M, 1%, ¼W, Metal

R16

Resistor, 1M, 1%, ¼W, Metal

R17

Resistor, 1M, 1%, ¼W, Metal

R18

Resistor, 2.7

, 1%, ¼W, Metal

Note 1

R19

Resistor, 2.7

, 1%, ¼W, Metal

Note 1

R20

Resistor, 2.7

, 1%, ¼W, Metal

Note 1

R21

Resistor, 820

, 1%, ¼W, Metal

Potentiometer, 4.7k

Multi turn

Potentiometer, 4.7k

Multi turn

P14

Potentiometer, 4.7k

Multi turn

Capacitor, electrolytic, 1µF, 16V

Note 2

Capacitor, electrolytic, 1µF, 16V

Note 2

Capacitor, electrolytic, 1µF, 16V

Note 2

Capacitor, ceramic, 3.3nF

Capacitor, ceramic, 2.2nF

Capacitor, ceramic, 3.3nF

Capacitor, ceramic, 560pF

C10

Capacitor, ceramic, 560pF

C11

Capacitor, ceramic, 560pF

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Parts List for Application Circuit: Figure 2 (Continued)

Item

Symbol

Description

Detail

C12

Capacitor, ceramic, 100nF

C13

Capacitor, ceramic, 820nF

Note 3

C14

Capacitor, ceramic, 100nF

Note 1: Resistor (R

, R

and R

) values are dependant upon the selected

values of the current transformer termination resistors R

, R

and R

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

current transformers

Note 3: Capacitor (C13) to be positioned as close to Supply Pins (V

& V

) of IC-1, as

possible.

Note 4: See the table below detailing the component values for the selected voltage

standard.

Item

Symbol

Description

Detail

PM9105AFA

PM9105AFE

115V

230V

200k

120k

R1A

180k

82k

200k

120k

R2A

180k

82k

200k

120k

R3A

180k

82k

ORDERING INFORMATION

Part Number

Description

PM9105AFA

3 X 115V, 3 X 80A Module

PM9105AFE

3 X 230V, 3 X 80A Module

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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 out web site:
http://www.sames.co.za

South African Micro-Electronic Systems (Pty) Ltd
P O Box 15888,

33 Eland Street,

Lynn East,

Koedoespoort Industrial Area,

0039

Pretoria,

Republic of South Africa,

Republic of South Africa

Tel:

012 333-6021

Tel:

Int +27 12 333-6021

Fax:

012 333-8071

Fax:

Int +27 12 333-8071

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.

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