Hardy HI 1756-2WS - Manual (Page 70)

HI 1756-WS MANUAL
7-8
Electrical See Figure 7-6
FIG. 7-6 GUIDELINES FOR INSTABILITIES ON FORMERLY
OPERATING SYSTEMS - ELECTRICAL
B1 Electrical
B1.1
Physical Grounding -
All common equipment share a common ground point.
Keep the ground cable length to earth ground as short as possible.
Install a new ground rod if the cable length is excessive.
B1.2
B1.3
B1.4
B1.5
B1.6
Cable -
Cuts or breaks in the loadcell cable insulation allow moisture to wick
into the cable and loadpoints. This can setup stray capacitance
charges and allow ground current to exist. This could create a highly
intermittent situation.
Loadcells -
Ground straps must be installed to provide a direct discharge path
to ground around the load points.
Vessel, Fill and discharge piping -
Ground all to a common point to eliminate electrical differences in
potential, and static build-up.
Cable Routing -
Separate high voltage sources and cables from low voltage signal cables.
Stay a minimum of 14 inches from Magnetic fields and SCR controls.
Avoid parallel high voltage and signal cable runs.
Cable Shielding -
Ground low voltage cable shields only at the controller end.
Grounding both cable ends will produce ground currents. Verify with
an ohm meter that the shield is only grounded at the weight controller.
Disconnect the shield at the controller and check for an open circuit
between ground and shield. Reconnect the shield to ground and
confirm a proper ground path from the Junction box to the controller.
Verify the shield is not connected to ground at the Junction Box.
Loadcell cable shields only pass thru the Junction Boxes and are not
connected to ground at that point
GOTO
B2
.