Schuetz Messtechnik GmbH

The precision holding device PWD2000/P is used for the determination of the electric resistance per meter of power and medium voltage cables. The measurement is based on the 4-pole method according to Kelvin in order to eliminate the feed line resistances. The measuring current is supplied via hydraulic operated jaws, the measuring voltage picked up via spring-supported taps, with a distance between the taps of 1000 mm (+/- 0,1mm).

The current jaws and thus the current feeding points are arranged at a sufficient distance to the taps in accordance with DIN/IEC to ensure a constant and uniform distribution of the current across the actual measuring distance.

Water flow version /W
The conductor sample to be measured (length. approx. 1400mm) is placed in a twin-trough. The inner trough, which is filled with flowing water when the pump is running, contains the potential bar for picking up the measuring voltage; it is here where the actual measurement takes place at a constant (water-)temperature. A connected Microohmmeter (e.g. MR300C-A or MR101-PWD) additionally measures the (water-) temperature via a probe and converts the previously measured resistance value to 20°C. The mechanical main function is like the PWD2000 P/L.

Air reposing version /A
There is one closed trough for the measuring system which is carefully isolated against flowing air from outside. After a given time the temperature of the sample is stable and identical to a special probe. The principle is the same as in the MAT2000T measuring system for stranding machines which is successful used with copper and aluminium cables.

Hydraulic current contacting
This standard holding device is suitable for aluminium and copper cables (stranded round and sector-shaped conductor samples) of a size between 10 and 2500 sq.mm.

In contrast to Copper which can be easily contacted to all single wires inside a sample Aluminium creates a problem. Due to the insulating oxide surface of each wire which will grow within minutes in presence of humidity and oxygen contacting all wires seems to be impossible. To solve this problem very special contact blades are used together with a very high pressure. This requires a hydraulic instead of a pneumatic or even manual driven system.

Sample tension /L
In many cases it is preferred to tension the cable, which does hardly slag anyway due to the cable support, by applying a longitudinal tensile force, in order to obtain even more accuratemeasuring results. This is done with mechanically adjustable longitudinal tension and its real effect is widely overestimated.