Thermo Scientific APEX 100 User Manual page 398

Glossary
Term
Sub-menu
Thresholds
VFD
Warning
WAF
X threshold
Page 398
Definition
Additional functions that are accessed from the
detector's Main Menu.
Thresholds are maintained for resistive and reactive
effects and, if exceeded, usually indicate a product is
present. High threshold values may indicate external
noise is present. See X threshold and R threshold.
Variable frequency drive
See WAF
Warning, alarm, or fault. Many of the detector's
functions use WAFs—in conjunction with a hardwired
external device—to notify you when some condition
occurs that needs your attention (a warning), to alert
you to something more urgent has happened (an
alarm), and to automatically take action (a fault) if
something more serious occurs. Warnings often
activate a light; an alarm, a buzzer; and a fault, a PLC
that shuts something down—such as the conveyor in a
conveyor application, or the flow of product a gravity-
feed or pipeline application.
Ferro-magnetic and electrically conductive materials
produce reactive effects. Iron is both electrically
conductive and is ferro-magnetic. As a result, the
properties of iron is different from a metal such as
copper, which is a strong electrical conductor. The X
threshold is a noise threshold for reactive signals.
Signals above the threshold usually indicate product or
metal contaminant signals. Excessive reactive signal
could indicate external noise (such as the presence of
VFD, EMI, and vibration), ground loops, static, and so
on is present in the area around the metal detector.
Thermo Scientific APEX User's Guide