Forum Discussion
MEXICOWANDERER wrote:
No.
One nick-name for these things is "Doughnut". Everything is inductive with the current transformer.
The hardest thing involved is to disconnect a hot wire and slip the doughnut down it to a convenient resting area. Much easier, faster and simpler than connecting a DC shunt.
A "split" current transformer takes care of slipping the wire through WITHOUT the need of disconnecting the wires.
SEE THIS LINK
However, current transformers are good only for AC, the do not work for DC circuits.
Current transformers are in fact a transformer, the AC lead going through the toroid is the primary winding and the secondary is the output leads. Depending on the ratio of the secondary windings you can "measure" a variety of low current to extremely high AC currents without the need to directly insert a meter into the circuit.
Allows for very remote metering of extremely high AC voltage and or AC current.
Additionally one MUST make sure if they are buying a current transformer that they know the difference between one that has a "burden" resistor or not. Current transformers MUST have a burden resistor across the output leads, this prevents lethal voltages from being present without a load attached to the leads.- Think "half of a transformer"
pianotuna wrote:
Hi,
So there is no direct connection to the wire carrying the current? Sorry to be so dumb.
There is no direct connection so electrical isolation is a big benefit.- No.
One nick-name for these things is "Doughnut". Everything is inductive with the current transformer.
The hardest thing involved is to disconnect a hot wire and slip the doughnut down it to a convenient resting area. Much easier, faster and simpler than connecting a DC shunt. - Hi,
So there is no direct connection to the wire carrying the current? Sorry to be so dumb. pianotuna wrote:
Hi,
So it uses a Hall Effect sensor?
No.
It's typically a toroid core with wire wrapped around the core. The current carrying conductor passes through the hole in the center.- It's a plastic ring Don. It has two small wires sticking out of it. You pass the hot AC power wire through the hole. Jab! So easy to install.
Then connect a teeny pair of wires (like 18 gauge speaker wire) to the two little current transformer wires (polarity doesn't matter here). The speaker wire then gets run to the meter and attach to two little screw-down contacts on the rear side. The AC power wires to the meter and run separate. What they do is solely provide power to the meter and a voltage reference point that the meter will show digitally.
These things are so easy to connect it isn't funny. I would however strongly recommend putting a 1/2 ampere glass fuse in line with the power lead. - Hi,
So it uses a Hall Effect sensor? pianotuna wrote:
...It works fine, but what is a current transformer?
Whenever current flows it generates a magnetic field.
A current transformer couples to this magnetic flux and generates a voltage proportional to the current.- Hi Mex,
It works fine, but what is a current transformer?
