Thermo Scientific APEX 100 User Manual page 284

Static Electricity
Sometimes, in conveyor applications, static electricity is generated when the belt and
slider-bed rub against each other. Because a moving or static charge is a form of
electrical current, moving or static charges may produce a magnetic field that randomly
interferes with the magnetic field produced by the search head. This type of interference
creates noise in the detector and may affect both the X- and R-channel.
Moving Metal
When metal moves through a magnetic field, it creates a current. Thus, any metal that
moves near the detector may cause interference in the detector—interference that is
easily confused with the effects of vibration.
Permanent Magnets and Electro-Magnets
If permanent magnets and electro-magnets are allowed near the detector, they can
cause interference—especially those that move or are situated very close to the
detector. Interference from these sources may affect with the detector's X- and R-
channels.
General Electrical Requirements
When choosing the AC power line for the detector, note that starting heavy electrical
machinery creates momentary volt-drops in the line. Such spikes can cause the detector
to trigger.
• When the control unit is mounted remotely from the search head, the cable
connecting it to the search head is of a specific type. Do not substitute or splice
on extra cable. Cable can be cut to length and is not sensitive to movement. If
required, contact Thermo Fisher Scientific—as described in the "Contacting
Thermo Fisher Scientific" section at the end of the manual—for extra cable or
cable information.
• Be sure to observe the following critical wiring conditions to ensure proper
connection of your detector
• Ensure main power is OFF.
• Earth all enclosures and conduits. An earth connection between all metal conduits
is required.
• Connect the shields only where shown.
• Check that all wires are tight in their connections.
• Never use a "megger" to check the wiring.
• All conduits should enter the bottom of the enclosure. Do not run conduit through
the top or sides of the enclosure.
Page 284 Thermo Scientific APEX User's Guide