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DC Resistance Unbalance Within a Pair
DC resistance unbalance within a pair is a measure how much the DC resistance of one wire differs from the resistance of the other wire within the same pair which is important to know when using Power over Ethernet. Read on to find out more about it.
DC resistance unbalance within a pair shows how much the resistance of one wire differs from the resistance of the other wire in a pair. Other terms for DC resistance unbalance within a pair are Pair Unbalance or Pair Ubl.
DC resistance unbalance within a pair should be as small as possible.
DC Resistance Unbalance Within a Pair
The term “DC resistance unbalance” is not only used for the resistance difference within a pair but also between pairs. Because of this it should always be made clear whether the DC resistance unbalance within a pair or between pairs is meant.
When devices are powered via the data cable it is done using direct current (DC). If the resistance of one wire differs from the resistance of the other wire within the same pair, it can lead to an uneven load which in turn can lead to an oversaturation of the transmitter’s transformer and thus to lower power transmission. An oversaturation of the receiver’s transformer can cause signal distortion and thus to data transmission problems.
Trouble-shooting tips if DC resistance unbalance within a pair tests fail
| Typical cause of the problem | This might help (without engagement) |
| Contacts in patch panel. outlet or plug are dirty | Clean contacts |
| Contacts in patch panel. outlet or plug are worn | Replace patch panel/outlet/plug |
| Contacts in patch panel. outlet or plug are corroded | Replace patch panel/outlet/plug |
| Wires in patch panel, outlet or plug are connected badly | Reconnect the wires |
| Wires in patch panel, outlet or plug have become loose | Reconnect the wires |
| Contacts of the test cord are dirty | Clean contacts |
| Contacts of the test cord are worn | Replace plug/test cord |
| Contacts of the test cord are coroded | Replace plug/test cord |
| Patch cord defective | Replace patch cord |
| Cable defective (material defect) | Replace cable |
Typical causes of DC resistance unbalance within a pair problems and what might help to solve them.
Contact
Dirk Traeger
