Hardy HI 1769-2WS - Manual (Page 72)

HI 1769-WS/HI 1769-2WS MANUAL
6-6
Electrical See Figure 6-4
FIG. 6-4 GUIDELINES FOR INSTABILITIES ON FORMERLY OPERAT-
ING SYSTEMS - ELECTRICAL
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.
B1.1
Cable -
Cust or breaks in the load cell insulation allow moisture to wick into the cable
and load points. This can setup stray capacitance charges and allow ground currents
to exist. This could create a highly intermittent situation. B1.2
Vessel, Fill and Discharge Piping -
Ground all to a common point to eliminate electrical differences in potential, and
static build-up.
B1.3
Load Cells -
Ground straps must be installed to provide a direct discharge path to ground around
the load points. B1.4
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.
B1.5
Cable Shielding -
Ground low voltage cable shields only at the controller end.
Gounding both cable ends will produce ground currents.
Verfy, with an ohm meter, 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 si not connected to ground at the Junction Box.
Load Cell cable shields only pass through the Junction Boxes and are not connected to
ground at that point. B1.6
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Electrical B1