Hello everyone, i am working with a couple of motors and found that when i start the motor the current starts as negative, then goes on to be positive as expected, anyone knows why?

the graphic looks something like this

 

What sort of motor? DC permanent magnet? DC series wound? DC parallel wound? AC SYnchronous? AC induction?
Was the motor already rotating when the power was switched on?

 

It may be just the way You are measuring,
Motors have a lot of Inductive-Reactance which can do strange things.
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What sort of motor? DC permanent magnet? DC series wound? DC parallel wound? AC SYnchronous? AC induction?
Was the motor already rotating when the power was switched on?

It was a DC

What sort of motor? DC permanent magnet? DC series wound? DC parallel wound? AC SYnchronous? AC induction?
Was the motor already rotating when the power was switched on?

It is a dc motor, not particularly sure about everything else, i thing is a permanent magnet and parallel. Just in case here is the amazon link of the motor
https://www.amazon.com/Planetary-Deceleration-Brushed-36GP-36ZYT-Precision/dp/B0B3MLK6LJ?th=1

 

What are you using for a power supply? How are you measuring the current?

 

What are you using for a power supply?

A lab bench power supply, here is the link to it
https://www.amazon.in/XACCU-Mastech-HY3005F-3-Triple-Linear/dp/B00I2EJCH8

 

A lab bench power supply, here is the link to it
https://www.amazon.in/XACCU-Mastech-HY3005F-3-Triple-Linear/dp/B00I2EJCH8

That supply has a maximum output current of 5A. That does not correlate to the current scale on your graph.
How are you measuring the current?

 

Yeah, that graph is not mine, but it is alike. The shape of the graph is the same, just scaled up. I am measuring the current with the int. circuit INA250A2PWR

 

Hello everyone, i am working with a couple of motors and found that when i start the motor the current starts as negative, then goes on to be positive as expected, anyone knows why?

the graphic looks something like this
View attachment 290660

So apparently it was not your motor, but this one! https://www.ametherm.com/blog/inrus...cuum-motors-experiencing-high-inrush-current/
What does your graph look like?