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DC Resistance Unbalance Between Pairs
DC resistance unbalance between pairs is a measure how much the DC resistance of one wire pair differs from the resistance of another pair which is important to know when using Power over Ethernet. Read on to find out more about it.
DC resistance unbalance between pairs shows how much the resistance of one wire pair differs from the resistance of another pair. Other terms for DC resistance unbalance between pairs are Unbalance Pair-to-pair, Pair-to-pair Unbalance or P2PUbl.
DC resistance unbalance between pairs should be as small as possible.
As the wire pairs in a data cable have a different twist, they have a different total length and thus a different DC resistance. When devices are powered via the data cable the electrical current running down one pair differs from that running down another pair. The uneven load 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 between pairs 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 |
| Twist of wire pairs of the patch cord differs too much | Replace patch cord |
| Patch cord defective | Replace patch cord |
| Twist of wire pairs of the horizontal cable differs too much | Replace cable |
| Cable defective (material defect) | Replace cable |
Typical causes of DC resistance unbalance between pairs problems and what might help to solve them.
Contact
Dirk Traeger
