ADVANTAGES OF CONTINUOUS MONITORING
OVER PERIODIC TESTING
Many customers are eliminating periodic testing and
are utilizing continuous monitoring to better ensure that
their products were manufactured in an ESD protected
environment. Full time continuous monitoring is superior
to periodic or pulsed testing, and can save a significant
amount of money in testing costs and rejected product.
Periodic testing detects failures after ESD susceptible
products have been manufactured. The costs of dealing
with the resulting catastrophic or latent defects can be
considerable. Multi-Mount Continuous Monitors eliminate
the need for users to test wrist straps and log the results;
by their function, these monitors satisfy the ISO 9000
and ANSI/ESD S20.20 test logging. ANSI/ESD S20.20
Paragraph 6.2.2.2 Personnel Grounding Guidance states “A
log should be maintained which verifies that personnel have
tested their personal grounding devices.” Per ESD-S1.1
Paragraph 6.1.3 “Daily (wrist strap system) testing may be
omitted if constant monitoring is used.”
WAVE DISTORTION DETECTION TECHNOLOGY
PROVIDES TRUE 100% CONTINUOUS MONITORING
From all the technical alternatives available, Desco
has chosen wave distortion technology for many of its
Continuous Monitor product offerings. Wave distortion
circuitry monitors current/voltage phase shifts and provides
true 100% continuous monitoring. Electrical current will
lead voltage at various points due to the combinations of
resistance and capacitive reactance. By monitoring these
“distortions” or phase shifts, the wave distortion Multi-Mount
Continuous Monitor will reliably determine if the circuit is
complete.
Wave distortion technology can be referred to “vector
impedance monitoring”. This description is valid as the
wave distortion technology measures the impedance at the
monitored banana jack and looks for changes in either the
capacitance or resistance of the circuit which includes the
wrist strap and its wearer. It uses filtering and time domain
sampling to filter out false signals caused by voltage offsets,
60 Hz fields and other electro-magnetic and electrostatic
interference.
In normal factory environments, and with persons whose
capacitance with respect to ground is within design limits
(5 feet tall 90 pound person to 6 foot 5 inch 250 pound
person), the Multi-Mount Continuous Monitor cannot be
“fooled”. It will provide a reliable alarm only when the
wrist strap becomes dysfunctional or unsafe according to
accepted industry standards. The Multi-Mount Continuous
Monitor is drift-free and designed to be insensitive to the
effects of squeezing or stretching the coil cord.
TB-3054
July 2011 Page 1 of 4
Multi-Mount Continuous Monitor
Operation, Installation, and Maintenance
Figure 1. Desco 19228 Multi-Mount Continuous Monitor
Description
Leading companies use continuous monitors as a cost
effective component in satisfying the paragraph 6.1.3
Compliance Verification Plan requirements of ANSI/
ESD S20.20. The Desco 19228 Multi-Mount Continuous
Monitor continuously monitors the integrity of one operator.
This monitor will provide virtually instantaneous notification
of static control equipment failures, eliminating the need
of periodic testing and costly record keeping. This unit
is highly cost effective as it is designed to monitor any
conventional single wire wrist strap and ground cord
system. Its small package and mounting tabs with holes
make it highly suitable to install on most any equipment
or work bench surface. In addition, optional mounting is
available using the provided adhesive-backed Velcro®
strips. Using either mounting method makes the
Multi-Mount Monitor suitable for most any machinery or
workbench even in hard to reach locations.
The Multi-Mount Continuous Monitor is a real time
instrument that ensures that critical ESD generators in a
sensitive area are effectively grounded. The instant an
operator’s wrist strap or cord fails, the monitor will issue
audible and visual (LEDs) alarms alerting the user and
supervisor of the problem.
The Parking Snap features provides a means for the
operator to disconnect wrist strap cord when normally
leaving work area without audible alarm sounding. It also
provides a means of wrist strap cord storage.
TECHNICAL BULLETIN TB-3054
Made in America
© 2011 DESCO INDUSTRIES INC.
Employee Owned
DESCO WEST
- 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
DESCO EAST
- One Colgate Way, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Web Site:
