Model 19665 Continuous Workstation Monitor, Dual Wire Copyright
2003 DESCO INDUSTRIES INC.
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Monitor Resistive Loop, Dual Operator/Dual Work Surface
Monitoring of two operators and two ground connections
independently. Dual Wire Continuous Monitors provide redundancy;
even if one wrist strap conductor is severed, operator has reliable
path-to-ground with other wire. Continuous Workstation Monitor,
Dual Wire, Programmable www.desco.com
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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, and then continuous monitoring should be
considered or even required. Per ESD-S1.1 paragraph 6.1.3 Frequency
of Functional Testing Daily [Wrist Strap] testing may be omitted if
constant monitoring is used. Continuous Workstation Monitor
www.desco.com
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What Should I Monitor? Operator resistance to ground
Workstation resistance to ground Operator charge buildup Want or
Need??? www.desco.com
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Considerations: All conductors must be grounded at all times to
protect against ESD Due to continuous movement; operators are the
greatest hazard to sensitive products The loss of a ground
connection can easily go unnoticed until yield is reduced. Then it
is too late! WHY NOT! What Should I Monitor? www.desco.com
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The decision is based on: ESD sensitivity of the products being
handled Type of process Compliance with existing standards Operator
HIGH and LOW resistance Workstation ground resistance Stainless
steel or dissipative material Ground reference What Should I
Monitor? www.desco.com
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The definition of ground is: A) 8 Volts B) 4 Volts C) 1.8 Volts
D) 0 Volts How is GROUND Defined? All conductors must be grounded A
continuous monitor is the grounding device www.desco.com
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Continuous Monitors The monitoring technology selected must be
compatible with device technologies There is a wide variety of
monitors available Various test methods Various test voltages
Various alarm condition Varying potential impact on process and
product Resistive loop monitors provide excellent protection
Resistive loop technology Continuous test voltage Pulsed test
voltage (mostly off) www.desco.com
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3M unit pulses test voltage 3M is actually off over 90% of the
time 3M pulses electrical current for only 0.2 seconds followed by
an unmonitored interval of 2 seconds Thus any resistance break must
be a continuous 2+ seconds. Not all intermittent failures are
caught! www.desco.com 3M Resistive Loop Monitoring
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Provides true 100% continuous monitoring 100% Monitoring means
detection of all intermittent failures! The response time of Desco
unit is 100 ms or 0.1 second It takes up to 2 seconds for the 3M
unit to respond ESD happens in 100 nanoseconds or.0000001 seconds
www.desco.com Desco Resistive Loop Monitoring
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The supply voltage then passes to the operator www.desco.com
Resistive Loop Monitoring - Theory
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Safe Monitor Status 3M 722 The supply voltage continues onto
the second half of the wrist strap assembly and finally to ground.
THE OPERATOR WILL HAVE A RESIDUAL VOLTAGE. www.desco.com Resistive
Loop Monitoring - Theory
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Safe Monitor Status When the operator comes in contact with
hand tools or fixtures while working on sensitive products... 3M
722 www.desco.com Resistive Loop Monitoring - Theory
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Safe Monitor Status the tool will rise to the voltage potential
of the operator. When the tool contacts the sensitive part... 3M
722 www.desco.com Resistive Loop Monitoring - Theory
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Safe Monitor Status A micro spark will be produced by the tool
& ESDS device, generating a current transient. MM, not HBM.
CURRENT TRANSIENT will range from 5mA to 55mA 3M 722 !!!! WHAM!!!!
www.desco.com Resistive Loop Monitoring - Theory
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HBM Vs. MM Human Body Model 1500 100 pf High resistance limits
the amount of current and energy produced during a discharge
Machine Model 0 200 pf Low resistance increases the amount of
current and energy produced during a discharge Using Machine Model
Operator becomes charged by the monitor and charges a tool that
then contacts an ESDS device. Low resistance, higher current and
energy, increased ESD risk! www.desco.com
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Safe Monitor Status The 19665 utilizes advanced circuitry which
dramatically reduces the operator voltage CURRENT TRANSIENT will
range from 1mA to 10mA 19665 www.desco.com Resistive Loop
Monitoring - Less is Better!!!
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Performance Summary www.desco.com 3M 722 V supply V operator
(Typical) Current Transient (Typical) Desco 19665 18v 8v 55mA 8v
4mA
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Alarm Conditions Operator High Resistance Low Resistance Charge
Detection Ground High Resistance Charge Detection
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Operator High Resistance 3M 722 YES 10 meg 19665 YES 10 meg
www.desco.com
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Low Resistance 3M 722 YES 1 meg 19665 YES 1 meg
www.desco.com
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Charge Detection 3M 722 NO 19665 NO www.desco.com
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Ground Failure 3M 722 YES 3.5meg 19665 YES 3.5meg 10 v 3 V
www.desco.com
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Alarm Status Comparison www.desco.com
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Systems Components Monitoring unit One remote with two
receptacles Mat ground wire System ground wire Mounting hardware
Power supply 3M 722 www.desco.com
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System Components Monitor unit Two operator remote receptacles
System ground wire Mat/table connection hardware Two mat
interconnect wires Two mat ground wires Mounting hardware Power
supply www.desco.com Desco 19665
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Feature: Patented Resistance Loop Benefit: Provides continuous
testing and verification of operators connection to ground
www.desco.com Continuous Workstation Monitor, Dual Wire, Resistive
Loop 19665 Dual Wire Monitor LED displays
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Feature: Monitoring of two operators and two ground connections
independently Benefit: Able to maintain two work operators and two
surfaces at the same time to eliminate the risk of ESD damage from
undetected wrist strap assemble failures www.desco.com Continuous
Workstation Monitor, Dual Wire, Resistive Loop
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Feature: Adjustable alarm level Benefit: Allows operator to
control volume of alarm www.desco.com Continuous Workstation
Monitor, Dual Wire, Resistive Loop
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Feature: Independent alarming conditions: Audible and Visual
Benefit: Operator will be able to see if noise level is high, or in
contrast, able to hear the alarm without looking at monitor
www.desco.com Continuous Workstation Monitor, Dual Wire, Resistive
Loop
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Feature: Fully compatible with the SCCN (Desco Semtronics
Static Control Communication Network) 62600 Benefit: Can be used to
automatically collect and monitor key operator status and fault
information www.desco.com Continuous Workstation Monitor, Dual
Wire, Resistive Loop
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Feature: Independent Safe lights for each operator and each
ground connection Benefit: Allows operator to visibly see status of
each operator www.desco.com Continuous Workstation Monitor, Dual
Wire, Resistive Loop
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Dimensions: 4.3W x 4.4D x 1.8H Power Supply: 110 VAC/60Hz
input, 12 VDC500mA output Rated Power Consumption: 3.6VA Suitable
for indoor use only at altitudes not exceeding 6500 ft (5km)
Maximum relative humidity is 80% up to 88 F (31 C) decreasing
linearly to 50% @ 104 F (40 C) Pollution Degree: 2 per IEC 644
Temperature Range: 41 F (5 C) to 104 F (40 C) Chassis: Stainless
Steel Housing Important: This appliance has a metal casing but the
earth connection is only used for operational purposes. It is
considered to be class I and testes as class II. The power supply
connection plug is accessible to the user and there is no safety
insulation inside the 62030. Therefore the insulation of the power
supply is critical Specifications www.desco.com
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Conclusion The 19665 Monitor provides the absolute best
grounding and ground protection WITHOUT EXCEPTION!!
www.desco.com
