SA2005M
ssaammeess
Resolution(RE)
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
rated current the resistor values should be selected for input
The RE input selects the summing mode for the programmable
adder as well as the dividing ratio for the LED output (LED
resolution). Thefollowingtableliststheoptionsavailable:
currents of 16µA . Referring to figure 8, the resistors R1 and
RMS
RE Pin
Summing Mode
Dividing Ratio
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 SA2005M.
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:
(LED Resolution)
VSS
Total sum
1
4
1
4
PH/DIR
OPEN
VDD
Total sum
Absolute sum
Absolute sum
The summing mode is the representation of the measured
energyandcanbeeitherofthefollowingtypes:
R1
R3
R5
= R
= R
= R
2
= ( I
= ( I
= ( I
L/ 16µARMS) x R29/ 2
4
6
L
L
/ 16µARMS ) x R30 / 2
/ 16µARMS ) x R31 / 2
Totalsum
This represents the total sum of the energy measured on all
three phases flowing through the current sensors. Negative
energyflowistakenintoconsideration.
Where:
I = Line current/CT-ratio
L
The value of the termination resistors should be less than the
resistance of the CT's secondary winding.
Absolutesum
This represents the sum of the energy measured on all three
phases, regardless of the direction of energy flow through the
currentsensors.
Voltage Reference Connection (VREF)
A bias resistor of 24kW provides an optimum bias conditions on
chip. Calibration of the SA2005M is done on the voltage sense
inputs as described in the Typical Application.
Impulses(IM)
The IM inputs selects between 1, 10, or 100 dividing ratio for
the motor drive outputs (counter resolution). Please note that
the device will not perform metering functions while in test
mode. Refer to the Using the RA, Re, Im inputs section for
furtherinformation.
Rated (RA)
The rated condition select pin allows the metering constants
(LED output and Motor Drive output) to remain unchanged for
different rated conditions having a 1:2:3 scaling ratio, for
example 230V/20A, 230V/40A and 230V/60A. This option
allows for the development of different rated meters requiring
minimal changes. The only changes to be implemented is the
selection of the current sense resistors for the expected rated
load currents and the selection of pins RA, RE and IM.
IM Pin
VSS
PH/DIR
VDD
Dividing Ratio (Counter Resolution)
100 (1P/KwH)
10 (10P/KwH)
1 (100P/KwH)
OPEN
Test Mode
RA Pin Rated Conditions Multiplying Ratio
1/3
2/3
3/3
VSS
Test Inputs (TEST)
PH/DIR
VDD
The TEST input is the manufacturers test pin and must be
connectedtoVSSinameteringapplication.
Fast LED output. The output is 1252Hz at rated
current and voltage inputs.
Open
At a rated condition of 230V/60A (13800W), setting the RA pin
to VDD (ratio set to 3/3) and the RE pin to VSS (LED
resolution) the LED pulse rate will be 3200 pulses/KWh. With a
combination of RA, RE and IM settings various rated condition
can easily be met. Refer to the Using the RA, RE, IM inputs
sectionforfurtherinformation.
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