Pressductor Pillowblock Load Cells Vertical Measuring PFCL 201 User manual

Fault Tracing of Load Cells, Junction Boxes and wiring

The load cell is very robust and can withstand high overloads. The data of a Pressductor load cell does not change slowly, but in steps, usually in connection with an event in the mill. Excessive overloading usually results in permanent shifting of the zero point.

Poor contact in the junction box causes intermittent faults. Both sensitivity and zero point may vary. Check all screw terminals. Do not use pins crimped to the connecting wires, as these often work loose after a time.

The cabling, especially the cable to the load cell, is the part that is most exposed to damage.

Since the resistance of the load cell windings is low, it is easy to check the load cells and cabling from the control unit.

Typical readings are 2 Ω  for the resistance of the primary winding and 9-12 Ω for the output impedance of the secondary winding.

Insulation faults in the cabling or the load cell may cause incorrect sensitivity or unstable zero point. When the load cell circuits have been isolated from earth and from the control unit at the discon nectable terminals, it is easy to measure the insulation from the control unit. If the cables are not routed correctly, they may pick up interference from other cables.

For circuit diagram applications, see the manual for the applicable control unit: Millmate Strip Tension Systems with Millmate Controller 400, 3BSE023139Rxxxx Web Tension Systems with Tension Electronics PFEA 111/112, 3BSE029380Rxxxx Web Tension Systems with Tension Electronics PFEA 113, 3BSE029382Rxxxx