sames
PM9103AP
SA9103 / SA9603C APPLICATION NOTE
FEATURES
n
Performs both power and energy
measurement
n
Meets the accuracy requirements for
Class 1 AC Watt hour meters
n
Protected against ESD
n
Total power consumption rating below
500mW (excluding current sensing)
SINGLE PHASE POWER/ENERGY METERING MODULE
SERIAL INTERFACE
n
Uses a shunt resistor for current
sensing
n
Operates over a wide temperature
range
n
Serial interface having a RS232
Protocol
DESCRIPTION
The SAMES single phase power/energy metering module, the PM9103AP, provides
energy data via a RS232 compatible serial interface.
Energy consumption is 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 power/energy meter is ideally suited for energy
calculations in applications using a -controller.
The application utilises the SAMES SA9103CP, SA9103EP or SA9603CP power
metering integrated circuits for power measurement.
As a safety measure, this application shows the current sensor connected to the neutral
line. In practice, the live line may be used for current sensing, provided that the supply
connections (MAINS) are reversed on the module.
4309
PDS038-SA9103-001
REV.C
11-08-98
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ABSOLUTE MAXIMUM RATINGS*
Parameter
Symbol
Min
Max
Unit
Supply Voltage (Note 1)
V
AC
540
V
Current Sense Input (Note 1)
V
IV
-2.5
+2.5
V
Storage Temperature
T
STG
-25
+125
C
Operating Temperature
T
O
-10
+70 (Note 2)
C
Max Current
I
MAX
800 (Note 3)
A
through Sensor
I
MAX
2000 (Note 4)
A
Note 1: Voltages are specified with reference to Live.
Note 2: The SA9103 and SA9603C integrated circuits are specified to operate over the
temperature range -10C to +70C. The module functionality will however
depend upon the external components used.
Note 3: t = 500ms
Note 4: t = 1ms
*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 operational sections of this
specification, is not implied. Exposure to Absolute Maximum Ratings for extended
periods may affect device reliability.
BLOCK DIAGRAM
SA9103
SA9603
POWER
METER
OPTO
COUPLER
SHUNT
POWER
SUPPLY
IN
OUT
NEUTRAL
NEUTRAL
NEUTRAL
LIVE
VOLTAGE SENSE
DR-01448
OPTO
COUPLER
D-sub CONNECTOR
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ELECTRICAL CHARACTERISTICS
(Over the temperature range -10C to +70C, unless otherwise specified. Power
consumption figures are applicable to the PM9103APE only.)
Parameter
Symbol
Min
Typ
Max
Unit
Condition
Supply Voltage
V
AC
180
230
265
V
PM9103APE
(Continuous)
90
115
135
V
PM9103APA
Power Measurement
P
RNG
-18400
18400
W
Specified
range
accuracy
Power Consumption
1
800
m W
V
AC
= 230V
Supply direct
from mains
Isolation Voltage
2
V
IS
2500
V
Continuous
Opto-coupler Output
Current
I
O
10
mA
V
OL
= 1V
Opto-coupler Input
Current
I
I
10
mA
Note 1: Power consumption specifications exclude power consumed by the current
sensor.
Note 2: Isolation voltage may be specified, depending on customer requirements.
CONNECTION DESCRIPTION
Designation
Description
MAINS
Voltage supply connection to Neutral line
Voltage supply connection to Live line
NEUTRAL IN
Connection to positive side of current sensor
NEUTRAL OUT
Connection to negative side of current sensor
SK1
Serial Input
D-sub connector
9-Pin
Serial Output
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FUNCTIONAL DESCRIPTION
1. Power Calculation
In the Application Circuit (see Figure 2), the output current from the current sensor
will be between 0 and 16A (0 to 80A through a shunt resistor of 625
). The current
input stage of the module, saturates at input currents greater than 18A
RMS
.
T h e
mains voltage (Voltage + 15% - 20%) is used to supply the circuitry with power and
to perform the power calculation, together with the current information from the
current sensor (shunt resistor).
The SA9103CP, SA9103EP and SA9603C integrated circuits may be adjusted to
accommodate any voltage or current values. The method for calculating external
component values is described in paragraph 6 (Circuit Description).
SAMES offers two evaluation module options, namely 230V/80A and 115V/80A.
The calculated power is integrated into a 22 bit integrator, which is accessable via
a serial interface having a RS232 protocol. The power calculation takes the power
factor into account.
2. Electrostatic Discharge (ESD) Protection
The device's inputs/outputs are protected against ESD according to the 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 sensor, when the supply is taken directly from
the mains.
4. Isolation
The serial interface is isolated from the module which is at mains potential, via two
opto-couplers. (In the event of the use of a current transformer for current sensing,
the opto-couplers would not be required.)
5. Serial Interface
Reading and resetting of the on-chip integrators may be performed using a Personel
Computer (PC). A standard serial cable should be used to connect SK1 to the PC.
The computers port settings are as follows:
19 200 Baud
1 Start bit
1 Stop bit
No parity bits
The Serial Interface allows for the following operations:
Read Integrator: The device transmits the current integrator status to the controller,
after the current measurement cycle has been completed (8 mains periods maximum).
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Reset Integrator: The integrator is reset without transmitting the integrator
status.
Read/Reset Integrator: The device transmits the integrator status and resets the
integrator after the current measurement cycle has been completed.
In a typical application, the system controller monitors the status of the on-chip
integrator using the "Read" command.
If after a "Read" command, the integrator value is sufficiently high, a "Read/Reset"
command from the controller causes the integrated circuit to complete the existing
measurement cycle, transmit the 16 most significant bits of the 22 bit integrator
via the Serial Output, to the controller and restart the integrator.
The most significant bit of the 16 bits, indicates the direction of energy consumption
measured (0 = Positive, 1 = Negative).
Refer to the SA9103C, SA9103E or SA9603C datasheets for the serial interface
command protocols.
6.
Circuit Description
The Application Circuit (figure 2) shows the components required for the serial
interface power metering module, using a shunt resistor for current sensing.
In this application the device requires +2.5V, 0V, -2.5V DC supply.
The most important external components are:
C
1
and C
2
are the outer loop capacitors of the two integrated oversampling A/D
converters. The value of these capacitors is 560pF. The actual values determine
signal to noise and stability performance. The tolerance should be within 10%.
C
3
and C
4
are the inner loop capacitors of the A/D converters. The optimum value
is 3.3nF. The actual values are uncritical. Values smaller than 0.5nF and larger
than 5nF should be avoided.
R
2
, R
1
and RSH are the resistors defining the current level into the current sense
input. The values should be selected for an input current of 16A
RMS
into the SA9103
/ SA9603C at maximum line current.
Values for RSH of less than 200
should be avoided.
R
1
= R
2
= I
L
/16A
RMS
* R
SH
/2.
Where
I
L
= Line current
RSH
= Shunt resistor/terminating resistor
R
3
, R
6
and R
4
set the current for the voltage sense input. The values should be
selected so that the input current into the voltage sense input (virtual ground) is set
to 14A
RMS
.
R
7
defines all on-chip bias and reference currents. With R
7
= 24k
, optimum
conditions are set.
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