Um...Me123
- Aug 6, 2005
- 174
- Joined
- Aug 6, 2005
- Messages
- 174
Hi @Um...Me123,
This is the same answer that @Ante has already given, but with some practical examples added.
When you read the label on a mains power supply extension cord which can be rolled up, you will be able to see two maximum values. When rolled up, the maximum power in Watts (and thus current, because the mains voltage stays the same) that is allowed, is always lower than that which you will see when fully unrolled. The reason for this is that heat may more easily be dissipated to the surrounding air than if it were rolled up and encapsulated. The same effect also plays a role when you wind your own transformer, for this encapsulated coil will not be able to dissipate heat as efficiently as wire surrounded by air only. Wire of coils of oil filed transformers on the other hand, may carry higher currents per square inch of coil wire than that of air cooled transformers used in consumer products. So, the open air ratings of this "Current Capacities of Wire Gauges" table may not be used for tightly wound or encapsulated wire, all other information stays unchanged.
Cryonic.
This is the same answer that @Ante has already given, but with some practical examples added.
When you read the label on a mains power supply extension cord which can be rolled up, you will be able to see two maximum values. When rolled up, the maximum power in Watts (and thus current, because the mains voltage stays the same) that is allowed, is always lower than that which you will see when fully unrolled. The reason for this is that heat may more easily be dissipated to the surrounding air than if it were rolled up and encapsulated. The same effect also plays a role when you wind your own transformer, for this encapsulated coil will not be able to dissipate heat as efficiently as wire surrounded by air only. Wire of coils of oil filed transformers on the other hand, may carry higher currents per square inch of coil wire than that of air cooled transformers used in consumer products. So, the open air ratings of this "Current Capacities of Wire Gauges" table may not be used for tightly wound or encapsulated wire, all other information stays unchanged.
Cryonic.
Last edited by a moderator:
Hi Cryonic,
There are two issues here when it comes to the rolled up cord, one is the direct ascending temperature from the current flow which occur rolled up or not. The other one is the inductively generated temperature due to the rolled up cord forming a coil which has very little to do with the wire area in relation to the current.
There are two issues here when it comes to the rolled up cord, one is the direct ascending temperature from the current flow which occur rolled up or not. The other one is the inductively generated temperature due to the rolled up cord forming a coil which has very little to do with the wire area in relation to the current.
Hi @Ante,
Very true indeed, but when concerning frequency, coil dimensions and form, coil winding layout, core material type, dielectricum, capacity, conductor material type, skin effect, temperature etc., things become increasingly complex and blurred to visualize or to understand. But, I felt that this would have been deviating too much off of the simplicity of the "Current Capacities of Wire Gauges" table presented by @Um...Me123. By keeping things as simple as possible, transparency into a certain matter at hand may be enhanced, and confusion kept to a minimum. But you rightly make this an issue that makes this Forum so interesting, rather than to see the horizon as an end point of visualization, only to be seen as the starting point of even more possibilities and depth.
Cryonic.
Very true indeed, but when concerning frequency, coil dimensions and form, coil winding layout, core material type, dielectricum, capacity, conductor material type, skin effect, temperature etc., things become increasingly complex and blurred to visualize or to understand. But, I felt that this would have been deviating too much off of the simplicity of the "Current Capacities of Wire Gauges" table presented by @Um...Me123. By keeping things as simple as possible, transparency into a certain matter at hand may be enhanced, and confusion kept to a minimum. But you rightly make this an issue that makes this Forum so interesting, rather than to see the horizon as an end point of visualization, only to be seen as the starting point of even more possibilities and depth.
Cryonic.
Last edited by a moderator:
