Desco 19246 Instruction Manual

No user adjustment required: The Continuous Monitor
is drift-free and designed to be insensitive to the effects of
squeezing or stretching the coil cord. It requires no user
adjustment.
The Dual Operator Workstation Continuous Monitor is a
real time instrument that ensures that critical ESD control
components in a sensitive area are effectively grounded. It
independently monitors the operator and the work surface.
The instant an operators wrist strap or cord fails, the monitor
will issue audible and visual alarms alerting the user of the
problem. In the same manner, the unit also confirms that a
path to ground of less than 10 megohms (1 x 10E7 ohms)
exists from the ESD protective work surface(s).
ADVANTAGES OF CONTINUOUS MONITORING
OVER PERIODIC TESTING
Many customers are eliminating periodic touch testing of wrist
straps 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 wrist strap failures after ESD susceptible products have
been manufactured. The costs of dealing with the resulting
catastrophic failures or latent defects can be considerable.
Dual Operator Workstation Continuous Monitors eliminate the
need for users to test wrist straps and log the results; by their
function, these monitors satisfy the ISO 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 the technical alternatives available, Desco designs
and manufactures many of its Continuous Monitor product
offerings using wave distortion technology . 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 Workstation Continuous
Monitor will reliably determine if the circuit is complete.
TB-3058 November 2011 Page 1 of 4
Dual Operator Workstation Continuous Monitor with
Satellites - Operation, Installation and Maintenance
Figure 1. Desco Dual Operator Continuous Monitor with
Satellites
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 Dual Operator Continuous Monitor with Satellites
continuously monitors the grounding integrity of two operators,
and two ESD worksurfaces’ path to ground. The monitor will
provide instantaneous notification of static control equipment
failures, and eliminates the need of costly and difficult to
supervise wrist strap logging record keeping. This unit is highly
cost effective as it is designed to monitor any conventional
single-wire wrist strap and ground cord system.
Per ESD Handbook TR 20.20 paragraph 5.3.2.4.4 Test
Frequency, “Because wrist straps have a finite life, it is
important to develop a test frequency that will guarantee
integrity of the system. Typical test programs recommend
that wrist straps that are used daily should be tested daily.
However, if the products that are being produced are of such
value that knowledge of a continuous, reliable ground is
needed, then continuous monitoring should be considered or
even required.”
The Dual Operator Continuous Monitor with Satellites is
available in two models.
*NASA Publication 1024-Anthropomorphic Source Book Volume 1:
“Anthropometry for Designers”
** Per ANSI/ESD S20.20 paragraph 6.0.3. Tailoring “This
document, or portions thereof, may not apply to all applications.
Tailoring is accomplished by evaluating the applicability of each
requirement for the specific application. Upon completion of the
evaluation, requirements may be added, modified or deleted.
Tailoring decisions, including rationale, shall be documented in the
ESD Control Program Plan.”
Model Voltage AC
19246 120 Volt
19247 220 Volt
DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • [phone] • Fax [phone]
DESCO EAST - One Colgate Way, Canton, MA 02021-1407 • [phone] • Fax [phone] • Website: Desco.com
TECHNICAL BULLETIN TB-3058
Made in the
United States of America
© 2011 DESCO INDUSTRIES INC.
Employee Owned
The Dual Operator Continuous Monitor with Satellites is an
impedance sensing device designed to monitor body types
from a 5th percentile female to a 95th percentile male. This
range covers a 5 foot tall 90 pound person to a 6 foot 5 inch
250 pound person in any production environment.* The 19246
is powered by a 120 VAC, 60/50 Hz, plug-in transformer which
also provides connection to ground.
19248 Satellite Remote Monitor

Wave distortion technology can be referred to as “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 Dual Operator Workstation Continuous Monitor cannot
be “fooled”. It will provide a reliable alarm only when the
wrist strap or work surface becomes dysfunctional or unsafe
according to accepted industry standards. The Dual Operator
Workstation 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 Dual Operator Workstation 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 more
expensive & less durable dual-wire cords and special wrist
straps. Dual-wire cords are expensive and are the weak
link of the system. They are the most likely component to
need replacement. Over a five year period this can make
a dual-wire system three times as expensive as a system
utilizing single-wire wrist straps and cords.
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 ESD events 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 microprocessor.”* The dual-wire system does not meet
all industry ESD S6.1 specifications, as the cords do not
meet the EOS/ESD Association guidelines for the 1 to 5
pound “breakaway force” requirement for ensuring a reliable
path-to-ground and preventing accidental disconnects.
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.
Installation
Confirm that worksurface(s) is 1 x 10E7 ohms or less and has
a conductive layer. Remove the monitor from its packaging
and inspect for any shipping damage. Included with each Dual
Operator and Dual Workstation Continuous Monitor should be:
1 Monitor Control unit
2 Satellite remote monitors with 6 mounting screws (19248)
2 7ft. remote cables for connection to satellites
1 120 / 220 VAC transformer
2 6' Work surface ground cord with additional ring terminals
2 6' Ground cord
4 Push and clinch snap (09863)
4 Counter Sink Washers
1 Certificate of Calibration
The Model 19246 / 19247 monitor control unit is normally
installed under the bench top toward the front edge of a
workstation where the LEDs are easily visible. The unit is
designed to be mounted using the flanges (See Figure 2).
Figure 2. Mounting the monitor
TB-3058 Page 2 of 4
DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • [phone] • Fax [phone]
DESCO EAST - One Colgate Way, Canton, MA 02021-1407 • [phone] • Fax [phone] • Web Site: Desco.com
*1981 article by Donald E. Frank - Electrical Overstress Electronic
Discharge Symposium Proceedings
© 2011 DESCO INDUSTRIES INC.
Employee Owned
Screws
Figure 3. Operating the 19246 / 19247 monitor
SATELLITE REMOTE
MONITORS.
The Satellite remote
monitors can be installed
up to 7 feet away from
the monitor control unit.
Two operators plus
two worksurfaces can be monitored at separate adjacent
workstation mat circuit maybe bypassed by a switch located
at the rear of the satellite. The satellite remote monitors are
available separately as item 19248. Also shown on each
Figure 3 shows the monitor as it is viewed from the front.

satellite remote unit is a supervisor ground connection jack
where a supervisor, guest, or equipment can be grounded.
Figure 4 shows the monitor control unit as it is viewed from the
rear, with the work surface wiring in place.
Figure 4. Wiring connection instructions for the 19246 / 19247
monitor control unit.
The following procedure will outline how to correctly wire the
19246 / 19247 monitor control unit to properly monitor an ESD
protected workstation.
1. Use the rear phone jack connections and connect the
Satellite Remote Units to the base unit with the phone cables.
See Figure 4 for wiring connection instructions.
2. Mat monitoring may be bypassed by using the switch
located inside a 1/4” hole at the rear of the satellite.
3. Verify that a ground cord is properly connected to snap
socket on one corner of the ESD worksurface. The other end
of the ground cord is to be attached to the workbench common
point ground. After Satellite Remote Units are mounted, route
wires using a direct route; try to avoid running wires adjacent
to metal.
4. Confirm that worksurface surface resistance is 1 x 10E7
ohms or less. Connect the ring terminal end of the worksurface
cord included with the unit to the screw on the back of the
satellite. Snap the other end to the worksurface grounding
point as shown in Figures 4 and 5.
5. A convenient 3-wire 120 VAC outlet should be located and
tested for proper wiring and grounding. We recommend Desco
Item 98130 AC Outlet Analyzer to verify proper wiring.
6. Plug the transformer into the outlet and connect the plug
into the back side of the monitor control unit. The green Work
Surface LED should be lit. The monitor control unit is now
ready for use. If the red Work Surface LED is flashing, check
the snap fastener and ground cords for proper connection.
Installation on Micastat®Laminate
Materials Needed:
2 Flush Mount Ground Laminate Inserts
1 Installation Tool for Flush Mount Insert
1. Install the Flush Mount Inserts first. It is recommended to
install one in the right back corner and the other in the left back
corner of the Micastat®laminated bench top.
2. Once both inserts are installed, cut the ground cord supplied
with the monitor into two pieces; make sure that the tinned end
is long enough to connect from the worksurface terminal on
the Satellite Remote Unit to one of the flush mount terminals
located under the bench.
3. The remaining wire can then be used to connect the other
flush mount terminal to ground using the supplied ring terminal.
The shrouded molded end can then be cut off.
When complete, one flush mount terminal will connect the
Micastat®laminate to ground while the other will connect
it to a satellite remote unit. The satellite remote unit then
monitors the ground connection between the two inserts,
and since Micastat®is the only ESD laminate made with
a physical uniform ground layer, it will monitor the entire
Micastat®surface ground. The wires will stay under the bench,
maximizing the usable space on the bench top.
Operation
When the satellite remote unit is installed and is connected to
a grounded ESD protective work surface, the monitor’s green
Work Surfaces LED’s and its two red Operator LED’s should
be on. The monitor takes 6 seconds to activate its alarm
circuitry when it is first plugged in.
To use the monitor:
1. Plug a wrist strap cord, into either of the Satellite remote
units marked “OPERATOR” on the front of the Satellite
remote unit. This automatically activates the selected operator
channel. The red Operator LED should turn on and the audio
alarm should beep.
2. Remove the charges from your body by making contact
with a properly grounded ESD worksurface. Snap the cord
to the wristband, which should fit snugly on your wrist. This
should silence the alarm and cause the LEDs to switch from
red to green. If this does not happen, check the coil cord for
continuity or damage. Examine your wristband and ensure that
it has a secure fit. If you have dry skin use ESD hand lotion
such as Menda Item 35660 Reztore™ ESD Hand Lotion.
When leaving the area a person can take the coil cord along
or unsnap the cord from wristband and attach the socket to
the Satellite remote unit snap that is labeled “Park”. This will
de-activate the alarm and allow you to leave the station. If the
cord is plugged into the jack marked “Operator” the monitor will
TB-3058 Page 3 of 4
DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • [phone] • Fax [phone]
DESCO EAST - One Colgate Way, Canton, MA 02021-1407 • [phone] • Fax [phone] • Web Site: Desco.com
© 2011 DESCO INDUSTRIES INC.
Employee Owned
TO
POWER
ADAPTER
WORKSTATION #2 WORKSTATION #1
TO SATELLITE
Figure 5. Installing cords on the worksurface.
Screw allows
ground cord to
be bolted to mat;
keeps cord from
disconnecting.
or

TB-3058 Page 4 of 4
alarm continuously until you either park the cord, or remove the
cord from the operator jack.
Whenever the continuity from the user to the satellite remote
unit is not maintained, the alarm sounds, the green Operator
LED turns off and the red Operator LED turns on.
Work Surface Channel
The 19246 / 19247’s Work Surface monitoring circuitry is
sufficiently sensitive to detect extremely low current, allowing
it to be used with mats having a resistance of up to 1x 10E7
ohms (10 megohms). If user desire not to monitor worksurface,
mat circuit can be bypassed with switch, located at the rear of
the satellite.
When the monitor is connected to a static dissipative work
surface, the amount of current that flows is a function of the
total resistance between the monitor and through the work
surface to ground. When the resistance of the work surface
is below a present threshold, the monitor will indicate good.
Conversely, if the resistance level is high when compared
to the monitor’s reference, the unit will alarm. This is an
integrating resistance measuring circuit. Therefore, it is
relatively insensitive to externally induced electromagnetic
fields. The resistance threshold is factory set to 10 megohms
(1 x 10E7 ohms). Custom worksurface range available upon
request. Call for details.
Note: Per ESD S6.1, Grounding paragraph 4.1.1 “Every
element to be grounded at an ESD protected station shall
be connected to the same common point ground.” The
ESD control plan should include a tailoring** statement
that continuous monitors are used and that consistent with
manufacturer’s design grounding is via AC adapter cord to
equipment ground.
Specifications
Test range of monitored circuit 500K - 10M ohms†
Supervisor Jack
Resistance to Ground 47k ohms typical
Work Surface Range 0 to 10 Megohms
(1 x 10E7 ohms)
Operating Voltage 120 VAC, 50-60 Hz
Wrist strap open circuit voltage 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
Long Term Drift <0.5% per Decade
(1st Decade is 1 hr)
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.
Maintenance and Calibration
The Dual Operator Workstation Continuous Monitor is solid
DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • [phone] • Fax [phone]
DESCO EAST - One Colgate Way, Canton, MA 02021-1407 • [phone] • Fax [phone] • Web Site: Desco.com
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.
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.
state and designed to be maintenance free. The 19246 and
19247 are calibrated to NIST traceable standards. There
are no user adjustments that can be made. Because of
the impedance sensing nature of the test circuit, special
equipment is required for calibration. We recommend using the
Desco 98220 Continuous Monitor Calibration Unit whenever
calibration is performed annually or any of the satellite
remotes are replaced. The Calibration Unit is an important
product which allows the customer to perform NIST traceable
calibration on continuous monitors and can be used to fulfill
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.”
The Desco 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.
† 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.
© 2011 DESCO INDUSTRIES INC.
Employee Owned