Correcting Open Loop Current Sensor Offset

Automation and Control Sensors Transducers
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Hello,

I am trying to use a Tamura L34S1T5D15T current sensor to measure high currents seen by an electrical bench setup. I am going to be measuring up to 1500A of current. I have tried some testing with the sensor, but I can’t seem to get the offset voltage to align with the datasheet for this sensor (linked below). Offset at 0V is listed at a max of +/- 0.020V but I am measuring -1.25V with no current flowing through the sensor. I do see the voltage react to current flowing through the sensor, but it does not align with expected values, and the big offset is also a concern.

Here is my setup:

I am powering the sensor via a dual source power supply setup providing +15V and -15V to the appropriate Vcc pins.

I have a 10k load resistance connected between Vout and the system GND reference.

The only two things I can think of, is maybe I have the direction backwards (arrow is supposed to follow electron flow vs conventional) or I am missing some other component on the output (maybe a capacitor is also needed).

Thanks for any help any of you can provide.

02_L34SxxxD15T_e_Current Sensor Data Sheet.pdf (167.7 KB)

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Hello @bgrovenger5,

Welcome to the TechForum.

There is a small caveat when dealing with open loop Hall-effect sensors. We see this in the datasheet as:

Offset voltage value is after removal of core hysteresis.

There is often a residual magnetization of the sensor’s core that will cause this offset. Unfortunately, this is not a constant and has “memory.” For example, assume a battery charging application. The zero current flow offset will be positive after charging. Sometime later, it will be negative after discharging the battery. An overload condition will cause an especially high offset.

This topic is explored in one of my previous articles.

Recommendations:

  1. Reverse the direction of current flow and to see if the offset changes.

  2. Degauss the core.

Happy soldering,

APDahlen

2 Likes
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I will try this out, thank you for the quick reply!

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Please let us know if it worked.

Best wishes,

Aaron