Issues using Hall Effect Current sensor with ADE7763 to measure current

Document created by analog-archivist Employee on Feb 23, 2016
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I am using hall effect current transducer device, ACS712, and I have problems
measuring stable current.
The line voltage that we are working with is 220 to 260 Volts. We are measuring
current levels which up to ~ 3Amps. The  ACS712 part is designed to have a
voltage output which swings around its power supply voltage/2. In this case,
therefore, we are expecting that the voltage representing the measured current
level will be swinging around 2.5 Volts. At the current levels we are
measuring, we are expecting the measured voltage to be swinging approximately
+/- 350mV around the 2.5Volt DC level


The problem with the Hall effect sensors is that they have a dc offset that is
variable with temperature. This offset may eat into the good input range the
ADE7763 may use and make some very high currents impossible to measure. (see
also Table 1, page 3 in the data sheet: ADE7763 has its own relatively big
offsets).  ACS712, requires output voltage shifting to bring it into the
ADE7763 +/-0.5Vpeak input voltage range.  If you have a common-mode voltage of
2.5V and a signal swing of +/-350mV, then the input voltage will be outside the
ADE7763's datasheet specification. We cannot guarantee the correct
functionality of the ADE7763, if the datasheet specifications are exceeded.
Maybe your can use current transformers instead. They do not have dc offsets.