seven_segment
Member level 2
Hi all. Just recently I have purchased a current transformer for a project I'm working on where I require a low voltage circuit to sense current on a 240v supply. Before I carry on with this post, the specs of the transformer are outlined below:
I should point out that this is the first time I have worked with current transformers. I've read up on them as much as possible, although there's still some confusion.
What I really want is a variable voltage between 0-5v DC in proportion to the primary current that I can feed straight into a microcontroller. I had hoped that I would be able to select a suitable burden resistor to get 0-5v AC on the secondary, and then convert this to AC. In theory this would mean I would need a 5v/5A = 1Ohm burden resistor. However, the specs on the transformer state 'VA 5'. I can only assume means that the maximum capacity of the secondary coil is 5VA, which limits me to 5VA/5A = 1v maximum voltage on the secondary.
I have no idea if I am applying the above calculations correctly, and would appreciate it if someone could shed some light on this area. Furthermore, could anyone explain to me the best way to get 5v DC when the secondary current is 5A AC (and values inbetween in proportion to the primary current) while not exceeding the specs of the transformer?
All help very gratefully appreciated.
40A:5A ratio
VA 5
Ith = 60 I 1n
Saturation Coefficient <6
I should point out that this is the first time I have worked with current transformers. I've read up on them as much as possible, although there's still some confusion.
What I really want is a variable voltage between 0-5v DC in proportion to the primary current that I can feed straight into a microcontroller. I had hoped that I would be able to select a suitable burden resistor to get 0-5v AC on the secondary, and then convert this to AC. In theory this would mean I would need a 5v/5A = 1Ohm burden resistor. However, the specs on the transformer state 'VA 5'. I can only assume means that the maximum capacity of the secondary coil is 5VA, which limits me to 5VA/5A = 1v maximum voltage on the secondary.
I have no idea if I am applying the above calculations correctly, and would appreciate it if someone could shed some light on this area. Furthermore, could anyone explain to me the best way to get 5v DC when the secondary current is 5A AC (and values inbetween in proportion to the primary current) while not exceeding the specs of the transformer?
All help very gratefully appreciated.