TECHNICAL BULLETIN TB-3028
Multi-Mount Continuous Monitor
Operation, Installation, and Maintenance
Made in America
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 storage.
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.
Figure 1. Desco 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 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 Desco Multi-Mount Continuous Monitor is available in
two models:
Model
19226
19227
Voltage AC
120
220
Calibration
NIST
NIST
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:
Desco.com
TB-3028
April 2011 Page 1 of 4
© 2011 DESCO INDUSTRIES INC.
Employee Owned
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.
ADVANTAGES OF WAVE DISTORTION AND
SINGLE-WIRE TECHNOLOGY
The Desco Multi-Mount Continuous Monitor allows the use
of any standard, single-wire wrist strap and coil cord. The
monitor/wrist strap/cord system life-cycle costs are by far
lower than alternative systems which require expensive &
fragile dual-wire cords and special wrist straps. Dual-wire
cords are expensive and are the weak link of the system,
the most likely component to need replacement. Over a
five year period, this can make the dual-wire system three
to five times as expensive as a system utilizing single-wire
wrist straps and cords. See Maintenance and Calibration
(page 4) to minimize life-cycle costs.
The dictionary defines constant as uniform and unchanging,
and continuous as uninterrupted. Nonetheless, some
dual-wire resistance monitors utilize a pulsed test current
and do not really provide continuous monitoring. For
example, during each 2.2 second pulse cycle of a leading
“constant” resistive monitor, electrical current is pulsed for
only 0.2 seconds followed by an unmonitored interval of
2 seconds. This leaves the user/wrist strap unmonitored
for over 90% of each cycle. Damaging static charges can
easily occur in the portion of the time in between the pulses.
The off period of 2 seconds equals 2 billion nanoseconds,
and “it takes only about 25 volts applied for 100
nanoseconds to blow most memories or microprocessors”.*
The dual-wire system does not reliably meet all industry
specifications, as the cords do not meet the EOS/ESD
S-1.0 paragraph 4.1.6, 1 to 5 pound “breakaway force”
requirement for operator safety.
By using the reliable wave distortion technology to
determine if the circuit is complete, there are no false
alarms. There is no need to adjust or tune the monitor to
a specific user or installation. The miniscule amount of
electrical current (less than 1 volt coil cord signal) required
to generate the waveform has never caused reported skin
irritation and is extremely safe for use in voltage sensitive
applications such as disk drive manufacturing.
A
H
G
F
B
C
D
E
Figure 2. Multi-Mount Continuous Monitor features and
components
Features and Components
(See Figure 2)
A. Status LEDs:
When the green LED is lit, the operator is
properly grounded. When the red LED is lit, the operator is
not properly grounded.
B. Monitored Operator Jack:
Where the operator inserts
the wrist cord banana plug.
C. Worksurface Ground LEDs:
When the green LED is
lit, the work surface mat is properly ground. When the red
LED is lit, the work surface mat is not properly grounded.
D. Operator Ground LEDs:
When the green LED is lit, the
operator is properly grounded. When the red LED is lit, the
operator is not properly grounded.
E. 4mm Parking Snap:
When touched by the operator, this
snap will deactivate the alarm for six seconds. This allows
time for the operator to disconnect the coil cord from the
wrist band and park it on this snap. While parked, the coil
cord disables the alarm, allowing the operator to leave the
workstation. The OPERATOR GROUND LED will remain
off while the cord is parked. Upon returning and removing
the coil cord from the parking snap, the operator has six
seconds to hook up to the wrist band before the alarm
sounds.
F. 24 VAC Power Jack:
Connect the power adapter here.
G. Mat Connection:
Monitors worksurface mat. NOTE: To
disable worksurface monitoring, shunt this terminal to the
neighboring GND terminal with a bus wire.
H. Mat Ground:
Grounds worksurface mat.
Installation
Remove the monitor from its packaging and inspect for
any shipping damage. Confirm that the work surface is 1
x 10E7 ohms or less and has a conductive layer such as
Dual Layer Rubber, Dissipative 3-Layer Vinyl, or Micastat®
Dissipative Laminate with conductive buried layers.
*1981 article by Donald E. Frank - Electrical Overstress /
Electronic Discharge Symposium Proceedings
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:
Desco.com
© 2011 DESCO INDUSTRIES INC.
Employee Owned
TB-3028
Page 2 of 4
Included with each Multi-Mount Continuous Monitor should be:
1
1
1
1
2
2
2
1
1
Multi-Mount Monitor
24VAC Power Adapter (120V for
19226,
220V for
19227)
6' Mat Monitor Cord (Black)
6' Mat Ground Cord (Green and Yellow)
Push and Clinch Snaps
Mounting screws
Counter Sink Washers
Set of hook and loop fasteners
Certificate of Calibration
Figure 4. Installation method #2 of the Multi-Mount
Continuous Monitor
I. A convenient 120VAC or 220VAC outlet should be
located and tested for proper wiring and grounding. We
recommend Desco Item
98130
AC Outlet Analyzer to verify
proper wiring and ground.
II. The Multi-Mount Continuous Monitor may be mounted to a
convenient location using the included mounting screws or
Velcro® set. See Figure 3 for installation set-up.
III. Install Screws and Washers or Push and Clinch snaps 12
to 72 inches apart from each other on the work surface
mat. Make sure that they pierce and clinch the bottom side
of the mat. (See Figure 3).
IV. Route the black ground cord to the monitor’s green terminal
block labeled MAT.
V. Route the green ground cord to the monitor’s green
terminal block labeled GND.
VI. Connect the power adapter to the monitor’s power jack
labeled “24VAC” and the other end to a proper voltage
source.
Screw allows ground cord to be
bolted to mat; keeps cord from
disconnecting.
Operation
When the Multi-Mount Continuous Monitor is installed to
an ESD protective work surface and grounded via a power
cord, the green WORKSURFACE GROUND LED and red
OPERATOR GROUND LED should be illuminated. The
monitor takes 6 seconds to activate its alarm circuitry when
it is first plugged in.
• The work surface resistance is measured between the two
cords installed to the mat worksurface (See Figure 3).
TO USE THE CONTINUOUS MONITOR:
1. Plug a wrist strap cord, not attached to the wristband,
into the monitored banana jack labeled OPR on the side
of the unit (See Figure 2). This automatically activates the
selected operator channel. The red operator LED should
illuminate.
2. Remove the charges from your body by making contact
with a properly grounded ESD worksurface. Snap the
cord to the wristband, and fit it snugly onto your wrist.
This should silence the audible alarm and cause the
OPERATOR GROUND LED to switch from red to green. If
this does not happen, examine the wrist cord for continuity
or damage and your wrist band to ensure that it is securely
fit. If you have dry skin, apply an approved dissipative hand
lotion such as Desco Reztore™ ESD Hand Lotion. When
leaving the area, the user can take the wrist cord along or
attach it to the monitor parking snap. The audible alarm will
shut off in approximately 6-8 seconds when operator wrist
cord is removed from unit and will instantly shut off when
the cord is attached to the parking snap.
NOTE: It is recommended that you use the Parking Snap
rather than continuously removing the Banana Plug from its
jack.
PARKING SNAP
The audible alarm is designed to alert both the operator and
supervisor. The parking snap feature allows the operator
to disconnect when leaving the work area without sounding
the audible alarm. It also provides a means for wrist cord
storage (red OPERATOR GROUND LED will illuminate).
When the operator touches the parking snap, the audible
alarm will disable for 6 seconds. The user can then
disconnect the wrist cord from the wrist band and attach it
to the parking snap for storage. If the operator removes
the wrist cord plug from the OPR banana jack, the audible
alarm will sound for 6-8 seconds.
or
10mm snaps need to pierce and clinch
bottom side of mat. Snaps need to be
12 to 72 inches apart
Power Adapter
Connection
Work Surface Mat
Figure 3. Installation method #1 of the Multi-Mount
Continuous Monitor
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:
Desco.com
© 2011 DESCO INDUSTRIES INC.
Employee Owned
TB-3028
Page 3 of 4
WORK SURFACE CHANNEL
The Multi-Mount Continuous Monitor monitoring circuitry is
sufficiently sensitive to detect extremely low current when
used with a worksurface with a conductive layer.
Maintenance and Calibration
The Multi-Mount Continuous Monitor is solid state and
designed to be maintenance free. The
19226
/
19227
is
calibrated to NIST traceable standards. There are no user
adjustments neccesary. Because of the wave distortion
sensing nature of the test circuit, special equipment is
required for calibration. We recommend that calibration
be performed using the Desco
98220
Continuous
Monitor Calibration Unit. The Calibration Unit is a most
important product which allows the customer to perform
NIST traceable calibration on continuous monitors. The
98220
is designed to be used on the shop floor at the
workstation, virtually eliminating downtime, verifying that
the continuous monitor is operating within tolerances. Per
ANSI/ESD S20.20 Paragraph 6.2.2.2 Personnel Grounding
Guidance, “Personnel should check constant monitoring
devices (when used) to ensure that they are functional and
operating before ESDS products are handled. In addition,
constant monitoring devices should be functionally checked
periodically to ensure that they are operating as designed.”
Specifications
:
Test range of monitored circuit
Operating Voltage
19226
19227
Work Surface Range
Wrist strap open circuit voltage
500K - 10M ohms†
120 VAC, 50/60 Hz
220 VAC, 50/60 Hz
10 Megohms
1.2 volts peak to peak @
1-2 MicroAmps
Mat test open circuit voltage
5 to 7.5 volts
Response time to alarm
<50 ms
Operating Temperature
0 - 40°C
Size
3.86"L x 2.10"W x .910"H
† This cannot be verified with standard DC test equipment.
The continuous monitor is an impedance sensing device
and the limits are determined by the magnitude and angle
of the impedance.
Limited Warranty
Desco expressly warrants that for a period of one (1) year from the
date of purchase Desco Continuous Monitors will be free of defects in
material (parts) and workmanship (labor). Within the warranty period,
a credit for purchase of replacement Desco Continuous Monitors,
or, at Desco’s option, the Continuous Monitor will be repaired or
replaced free of charge. If product credit is issued, the amount will
be calculated by multiplying the unused portion of the expected one
year life times the original unit purchase price. Call our Customer
Service Department at 909-627-8178 (Chino, CA) or 781-821-8370
(Canton, MA) for a Return Material Authorization (RMA) and proper
shipping instructions and address. Please include a copy of your
original packing slip, invoice, or other proof of date of purchase. Any
unit under warranty should be shipped prepaid to the Desco factory.
Warranty replacements will take approximately two weeks.
If your unit is out of warranty, call our Customer Service Department
at 909-627-8178 (Chino, CA) or 781-821-8370 (Canton, MA) for a
Return Material Authorization (RMA) and proper shipping instructions
and address. Desco will quote repair charges necessary to bring your
unit up to factory standards.
Figure 5. Using the Multi-Mount Continuous Monitor
Note: Work surface must have a conductive layer such
as Dual Layer Rubber or Dissipative 3-Layer Vinyl or
Micastat® Dissipative Laminate with conductive buried
layers. Desco Continuous Monitors are not recommended
for use with homogeneous matting.
Warranty Exclusions
THE FOREGOING EXPRESS WARRANTY IS MADE IN LIEU
OF ALL OTHER PRODUCT WARRANTIES, EXPRESSED AND
IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE WHICH ARE SPECIFICALLY
DISCLAIMED. The express warranty will not apply to defects or
damage due to accidents, neglect, misuse, alterations, operator error,
or failure to properly maintain, clean or repair products.
Limit of Liability
In no event will Desco or any seller be responsible or liable for any
injury, loss or damage, direct or consequential, arising out of the
use of or the inability to use the product. Before using, users shall
determine the suitability of the product for their intended use, and
users assume all risk and liability whatsoever in connection therewith
.
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:
Desco.com
© 2011 DESCO INDUSTRIES INC.
Employee Owned
TB-3028
Page 4 of 4
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