SA9105 APPLICATION NOTE
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PM9105AF
THREE PHASE POWER/ENERGY METERING MODULE
PULSE OUTPUT
FEATURES
n Performs one, two or three phase power
and energy measurement
n Meets the accuracy requirements for
Class 1 AC Watt hour meters
n Operates over a wide Temperature
Range
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.
n Uses current transformers for current
sensing
n Three pulse rate outputs available
n Protected agianst ESD
4310 PDS038-SA9105-001 Rev. B 13-09-95
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BLOCK DIAGRAM
ABSOLUTE MAXIMUM RATINGS *
Parameter Symbol Min Max Unit
Supply Voltage (Note 1) V
Storage Temperature T
Operating Temperature (Note 2) T
AC
STG
O
-25 +125 °C
-10 +70 °C
540 V
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) V
AC
180 230 265 V PM9105AFE
(Continuous) 90 115 138 V PM9105AFA
Frequency Output FOUTX Refer to applicable IC data sheet
Power Consumption
1
100 mW VDD = 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
1. 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
. The mains voltage (mains voltage + 15% - 20%) is used for
RMS
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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PM9105AF
For rated conditions, the signals into the current and voltage sensor inputs are set
as follows:
Current sensor input currents: 16µ A
Voltage sensor input currents: 14µ A
RMS
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 F OUT3 the output frequency is
FOUT1/290.
2. 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.
3. Power Consumption
The overall power consumption rating for this power metering application (Figure 2),
is under 500mW, excluding the current sensors.
4. Isolation
The reference for the unit is connected to neutral.
5. 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:
C7, C9, C10 and C11 are the outer loop capacitors for the integrated oversampling
A/D converters. The typical value of C7 is 2.2nF and the value of C9, C10 and C11 is
560pF.
The actual values determine the signal to noise and stability performance. The
tolerances should be within ± 10%.
C4, C5, C6 and C8 are the inner loop capacitors for the integrated oversampling
A/D converters. The typical value of C4, C5, C6 and C8 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 (R8 ..R13).
The resistor values should be selected for an input current of 16µA into the SA9105
at the rated line current.
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The values of these resistors should be calculated as follows:
Phase 1:
R8 = R9 = (IL1/16µA) x R18/2
Phase 2:
R10 = R11 = (IL2/16µA) x R19/2
Phase 3:
R12 = R13 = (IL3/16µA) x R20/2
Where I
LX
= Secondary CT current at rated conditions.
R18, R19 and R20= Termination resistors of the three current transformers.
R
+ R1A, R4 and R15 set the current for the phase 1 voltage sense input. R2 + R2A,
1
R5 + P5 and R16 set the current for phase 2 and R3 + R3A, R6 + P6 and R17 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 14µA at nominal line voltage. Capacitors C1,
C2 and C3 are for decoupling and phase compensation.
R
+ P14 defines all on-chip bias and reference currents. With R14 + P14 = 24kΩ,
14
optimum conditions are set. P14 may be varied within ± 10% for calibration purposes.
Any changes to R
will affect the output quadratically (i.e: ∆R = +5%, ∆FOUT =
14
+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 1: Connection Diagram
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Figure 2: Application for Three Phase Power/Energy Measurement.
PM9105AF
MAINS VOLTAGES
PH1
PH2
PH3
N
0V
R18
CT1
R19
CT2
R20
CT3
2.5V
0V
5V
2.5V
C4
C5
C6
C7
C8
C12
R1
R2
R3
R8
R9
R10
R11
R12
R13
XTAL
R1A
R2A
R3A
34
44
11
13
14
15
16
17
SA9105
18
PLCC-44
19
20
IC-1
21
22
23
25
26
27
28
29
32
33
30
DR-00882
24
12
10
C9
9
8
C10
7
6
R15
C11
R16
R17
C13
0V
C1+
C2
+
C3
+
5V
FOUT3
FOUT2
FOUT1
0V
R6
R5 R4 R21
P6
P5
0V
5
4
3
2
1
43
42
41
40
39
38
37
36
35
31
5V
R7
2.5V
C14
0V
R14
P14
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Parts List for Application Circuit: Figure 2
Item Symbol Description Detail
1 IC-1 SA9105AF/SA9105EF PLCC-44
2 XTAL Crystal, 3.5795 MHz TV Crystal
3 R1 Resistor, 1%, ¼W, Metal Note 4
4 R1A Resistor, 1%, ¼W, Metal Note 4
5 R2 Resistor, 1%, ¼W, Metal Note 4
6 R2A Resistor, 1%, ¼W, Metal Note 4
7 R3 Resistor, 1%, ¼W, Metal Note 4
8 R3A Resistor, 1%, ¼W, Metal Note 4
9 R4 Resistor, 24k, 1%, ¼W, Metal
10 R5 Resistor, 22k, 1%, ¼W, Metal
11 R6 Resistor, 22k, 1%, ¼W, Metal
12 R7 Resistor, 820Ω, 1%, ¼W, Metal
13 R8 Resistor, 2.7k, 1%, ¼W, Metal Note 1
14 R9 Resistor, 2.7k, 1%, ¼W, Metal Note 1
15 R10 Resistor, 2.7k, 1%, ¼W, Metal Note 1
16 R11 Resistor, 2.7k, 1%, ¼W, Metal Note 1
17 R12 Resistor, 2.7k, 1%, ¼W, Metal Note 1
18 R13 Resistor, 2.7k, 1%, ¼W, Metal Note 1
19 R14 Resistor, 22k, 1%, ¼W, Metal
20 R15 Resistor, 1M, 1%, ¼W, Metal
21 R16 Resistor, 1M, 1%, ¼W, Metal
22 R17 Resistor, 1M, 1%, ¼W, Metal
23 R18 Resistor, 2.7Ω , 1%, ¼W, Metal Note 1
24 R19 Resistor, 2.7Ω , 1%, ¼W, Metal Note 1
25 R20 Resistor, 2.7Ω , 1%, ¼W, Metal Note 1
26 R21 Resistor, 820Ω , 1%, ¼W, Metal
27 P5 Potentiometer, 4.7k Multi turn
28 P6 Potentiometer, 4.7k Multi turn
29 P14 Potentiometer, 4.7k Multi turn
30 C1 Capacitor, electrolytic, 1µF, 16V Note 2
31 C2 Capacitor, electrolytic, 1µF, 16V Note 2
32 C3 Capacitor, electrolytic, 1µF, 16V Note 2
33 C4 Capacitor, ceramic, 3.3nF
34 C5 Capacitor, ceramic, 3.3nF
35 C6 Capacitor, ceramic, 3.3nF
36 C7 Capacitor, ceramic, 2.2nF
37 C8 Capacitor, ceramic, 3.3nF
38 C9 Capacitor, ceramic, 560pF
39 C10 Capacitor, ceramic, 560pF
40 C11 Capacitor, ceramic, 560pF
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Parts List for Application Circuit: Figure 2 (Continued)
Item Symbol Description Detail
41 C12 Capacitor, ceramic, 100nF
42 C13 Capacitor, ceramic, 820nF Note 3
43 C14 Capacitor, ceramic, 100nF
Note 1: Resistor (R8, R9, R10, R11, R12 and R13) values are dependant upon the selected
values of the current transformer termination resistors R18, R19 and R20.
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 (VDD & VSS) of IC-1, as
possible.
Note 4: See the table below detailing the component values for the selected voltage
standard.
Description
Item Symbol
PM9105AFA PM9105AFE
Detail
115V 230V
3 R1 200kΩ 120kΩ
4 R1A 180kΩ 82kΩ
5 R2 200kΩ 120kΩ
6 R2A 180kΩ 82kΩ
7 R3 200kΩ 120kΩ
8 R3A 180kΩ 82kΩ
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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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 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
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