TB-2084
Page 4 of 4
© 2001 DESCO INDUSTRIES INC.
Employee Owned
Whenever the coil cord is accidentally withdrawn from the
monitor, or if continuity from the user to the monitor is not
maintained, the alarm sounds, the green Operator LED
turns off and the red Operator LED turns on.
COMPUTER INTERFACE
The model 19208 monitor also incorporates logic output
circuitry. The unit is designed with an open collector circuit
that can be set up to activate remote sirens, alarms or
interface with a computer. The open collector circuit is
accessible through the terminal screw on back of the
monitor. See figure 4 for location.
WORK SURFACE CHANNEL
The 19208’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 5 x 10
8
ohms.
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 500 megohms. Custom worksurface range available
upon request. Call for details.
Specifications
Work Surface Limit*
Set to 500 Megohms
Operating Voltage
120 VAC, 50-60 Hz
Response time to alarm
< 50 mS
Operating Temperature
0 - 40°C
Long Term Drift
<0.5% per Decade
(1st Decade is 1 hr)
Size (less bracket)
3.25 x 4.75 x 1.1
OPEN COLLECTOR OUTPUT
Fail-Safe:
For fail safe operation, an active low is required.
If the monitor detects an operator-grounding fault, the open
collector port goes low (with respect to the green wire
ground).
One-Wire:
Since the monitor detects that there is a low
resistance between the green wire ground and the neutral
conductor in the branch circuit, less than 1K ohms, the
green wire ground serves as the reference or the second
wire between the monitor and its remote warning device.
The open collector port is the other.
DESCO WEST
- 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
DESCO EAST
- 90 Hudson Road, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Web Site: http://www.desco.com
*Limits can be varied and set to 1 gigohm maximum.
Limited Warranty
Desco expressly warrants that for a period of five (5) years 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 five 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.
Specifications:
V (open circuit)
<20 V
I (short circuit)
200 uA
Pull-up to 15V
>50 uA (Active)
Pull-up to 5V
>150 uA (Active)
Pull-down to 0.5V
>400 uA (Active)
Third-state HiZ
>100 K ohms (unit unplugged)
Maintenance and Calibration
The Dual Operator Workstation Continuous Monitor is solid
state and designed to be maintenance free. The 19208 and
19209 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 that
calibration be performed annually, using the #98220
Continuous Monitor Calibration Unit.
Prior to calibration,
disconnect Remote Jacks (if used) from the unit.
Remote Jacks may cause intermittencies in calibration.
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.
