I have a setup using 3 hall effect current sensors and my goal is to measure the DC current flowing through cables. The sensors are HSTS016L. I attached a picture of the manual. The sensors have 4 pins GND, +5V, Vref and Vout. The Vref are constant for all 3 sensors but they are not exactly the same values for all 3 (2499.7mV, 2509.7mV and 2507.2mV). The Vout decreases when the amount of current in the cable increases. So for example: Sensor 1: @2,7A Vout is 2464,6mV and @5,5A is 2371,9mV My first question is what should I be measuring? the voltage between Vout and the ground or the voltage between Vref and Vout? The second question is how to determine the amount of current flowing in the cable? Is the only way by making reference measurements for each sensor?
You should measure Vout with respect to ground.
If you zoom out the picture there is a small voltmeter connected to Vout (see below). So, that's their suggested way to measure.
In the datasheet of another Hall split core sensor (HSTS08) the word "suspensibility" is written behind Vref. I think this is the magnetic susceptibility and the defiation from 2.5V is a measure of the magnetic susceptibility of the Hall sensor. But I cannot find documentation for it.
You could try and play around by measure a significant current with the device and check how the reference voltage changes. Next, revert this significant current and see if the reference voltage returns to it's original value.
But best way of course is just contact them about Vref on https://poweruc.com/pages/contact.