ACM ST200 User manual

ST200
ST300
SERIES
INSTRUCTIONS
AMC-ST200 Electrochemical
AMC-ST350 Solid State
AMC-ST360 Catalytic
INSTALLATION AND OPERATING
INSTRUCTIONS FOR THE AMC-ST200, ST350,
ST360 TRANSMITTERS
IMPORTANT:
Please read these installation and operating instructions
completely and carefully before starting.
.........................................................................................................................................Copyright 1999
The Armstrong Monitoring Corporation (AMC)
[phone] -Å
[phone] -(Fax)
1 [phone] -Å(U.S. Toll Free)

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
-ii -
WARRANTY .......................................................................................................1
LIABILITY...........................................................................................................1
MODIFICATIONS AND SUBSTITUTIONS......................................................1
PRODUCT RETURN ...........................................................................................2
PRODUCT INFORMATION...............................................................................2
FACTORY CALIBRATION................................................................................2
SECTION I.......................................................................................................................3
GENERAL DESCRIPTION .............................................................................................3
1.1 DESCRIPTION..............................................................................................3
1.2 SPECIFICATIONS........................................................................................5
1.2.1 SENSOR VOLTAGE (ST350/360 Series)...................................................5
1.2.2 SIGNAL OUTPUT......................................................................................5
1.2.3 POWER SUPPLY .......................................................................................5
1.2.4 CALIBRATION RANGE............................................................................5
1.2.5 CALIBRATION RESOLUTION.................................................................5
1.2.6 ACCURACY...............................................................................................6
1.2.7 AMBIENT TEMPERATURE RANGE ........................................................6
1.2.8 TEMPERATURE DRIFT.............................................................................6
1.2.9 HOUSING:..................................................................................................6
SECTION II .....................................................................................................................7
INSTALLATION .............................................................................................................7
2.1 MOUNTING..................................................................................................7
2.2 ELECTRICAL CONNECTIONS...................................................................7
SECTION III....................................................................................................................9
OPERATING PROCEDURES .........................................................................................9
3.1 NORMAL MODE OPERATION...................................................................9
3.2 OVERRANGE................................................................................................9
3.3 ROUTINE CALIBRATIONS USING CAL MODE.......................................10
3.4 UNITY GAIN MODE ....................................................................................10
3.5 DELAY MODES ............................................................................................11
3.5.1 POWER UP DELAY............................................................................11
3.5.2 CAL MODE EXIT DELAY..................................................................11
3.5.3 AUTOMATIC CAL MODE EXIT TIMER...........................................12
3.5.4 ABORTING THE DELAY MODES.....................................................12
3.6 FAULT CONDITIONS..................................................................................12
3.7 BACK-UP OF CALIBRATION VALUES DURING POWER LOSS...........12
3.8 LCD READOUT CALIBRATION PROCEDURE .........................................12

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
-ii -
SECTION IV....................................................................................................................15
MODEL ST350 & 360 SOLID STATE AND CATALYTIC SERIES ..............................15
4.1 GENERAL DESCRIPTION ...........................................................................15
4.2 INITIAL START-UP AND CALIBRATION PROCEDURE .........................15
4.2.1 SENSOR VOLTAGE ADJUSTMENT.................................................16
4.2.1 MONITORING THE VOUT TEST POINT.........................................16
4.2.2 BALANCE ADJUSTMENT.................................................................17
4.2.3 ST350/ST360 SERIES INITIAL FIXED GAIN ADJUSTMENT.........17
4.3 SENSOR FAULT SUPERVISION.................................................................18
SECTION V.....................................................................................................................20
MODEL ST200 ELECTROCHEMICAL SERIES ............................................................20
5.1 GENERAL DESCRIPTIONS.........................................................................20
5.2 INITIAL START-UP AND CALIBRATION PROCEDURE .........................20
5.2.1 SENSOR RESPONSE COEFFICIENT...............................................21
5.2.2 SELECTING PRE-AMP GAIN RESISTOR R13.................................21
5.2.3 INITIAL FIXED GAIN ADJUSTMENT..............................................21
5.3 SENSOR FAULT SUPERVISION:................................................................23
SECTION VI....................................................................................................................24
OPTIONAL FEATURES..................................................................................................24
6.1 GENERAL DESCRIPTION ...........................................................................24
6.2 ISOLATED 4-20 MILLIAMPERE OUTPUT OPTION .................................24
6.3 MODBUS® RS-485 SERIAL INTERFACE OPTION ..................................25
6.3.1 RTU ADDRESS ...................................................................................26
6.3.2 DATA REGISTERS AND FUNCTION CODE...................................26
6.4 ALARM RELAYS OPTION ..........................................................................26
6.4.1 LATCHING ALARMS:........................................................................27
6.4.2 FAIL SAFE ALARMS:.........................................................................27
SECTION VII...................................................................................................................29
CUSTOMER SUPPORT..................................................................................................29
7.1 TECHNICAL SERVICE:................................................................................29
7.2 HEAD OFFICE..............................................................................................29
SECTION VIII .................................................................................................................30
PHYSICAL DIMENSIONS.............................................................................................30

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
-1-
WARRANTY:
The AMC-ST Series Super Transmitter is warranted against defects in material and
workmanship for a period of two years from date of delivery (For sensor, see 1.2 sensor
Specifications). During the warranty period, we will repair or replace components that
prove to be defective in the opinion of The Armstrong Monitoring Corporation
(AMC). We are not liable for auxiliary interfaced equipment, nor consequential damage.
This warranty shall not apply to any product, which has been modified in any way, which
has been repaired by any other party other than qualified technician or authorized AMC
representative, or when such failure is due to misuse or conditions of use.
LIABILITY:
All AMC products must be installed and maintained according to instructions. Only
qualified technicians should install and maintain the equipment.
AMC shall have no liability arising from auxiliary interfaced equipment for consequential
damage, or the installation and operation of this equipment. AMC shall have no liability
for labour or freight costs, or any other costs or charges in excess of the amount of the
invoice for the products.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESSED OR IMPLIED, AND SPECIFICALLY THE WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
THERE ARE NO WARRANTIES, WHICH EXTEND BEYOND THE
DESCRIPTION ON THE FACE THEREOF.
MODIFICATIONS AND SUBSTITUTIONS:
Due to an ongoing development program, AMC reserves the right to substitute
components and change specifications at any time without incurring and
obligations.

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
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PRODUCT RETURN:
All products returned for warranty service will be prepaid freight and they will only be
accepted with an R.M.A. number issued by AMC. All products returned to the client
will be freight collect.
PRODUCT INFORMATION:
Transmitter/Sensor unit Order Number ……..
Transmitter Part Number …………………….
Transmitter Serial Number …………………..
Sensor Part Number ………………………….
Power Supply Requirement 18-30 VDC; less than 4 Watts
Signal Output Load 4-2OmA into 800 ohms max.
FACTORY CALIBRATION:
Gas Type ………………………………………
Zero Gas, at 4mA Signal ………………………
Gas Concentration at 20 mA Signal …………..

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
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SECTION I
GENERAL DESCRIPTION
1.1 DESCRIPTION:
This manual describes the AMC microprocessor based ST Series Non-Intrusive
Transmitters. Three models of the ST Series are described within this manual.
The ST360 Series accepts catalytic bead combustible sensors. The ST350 Series is a
non-intrusive transmitter used with solid state sensors. The ST200 Series accepts
electrochemical toxic and oxygen sensors.
Several options are available to enhance ST Series Non-Intrusive Transmitters
capabilities. These include an isolated 4-20 mA output, an RS-485 Modbus® serial
interface, or an alarm providing 5 A form C relays for fault, warn and high alarm
conditions.
The AMC ST Series Non-Intrusive Transmitters accept a wide range of gas detection
sensors. These sensors are directly connected to the ST Series without need of other
transmitters or electronics. Supplied transmitters are factory calibrated. A 4-20 mA
output and 3 1/2 digit LCD readout provide analog and visual indications of gas
concentration. Magnetic sensors allow complete "end to end" calibrations to be
performed to the transmitter section without opening the explosion-proof enclosure.
This is especially useful when the area is classified as potentially hazardous and
declassification is required to open enclosures.
FAULT conditions, such as LEL sensor opens and shorts, missing EC sensor, or
negative drift below 1.6 mA (-15% of full scale), are detected and flagged by the ST
Series. During these FAULT conditions the 4-20 mA output is held at 0 mA and the
KEYPAD/FAULT LED indicator is illuminated.

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
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The only tool required to perform calibrations is a small magnet, which is provided on a
key chain. The integral 3 1/2 digit LCD readout may be calibrated for direct reading in
engineering units such as percent of LEL (lower explosive limit) or PPM (parts per
million).
Before calibration is possible, the ST Series must be properly activated by entering the
CAL MODE. This is done by briefly holding the magnet to a location on the panel
marked by a small dot. The ST Series will respond by illuminating a left hand arrow on
the LCD readout. This serves as a "pass-key" and makes it difficult for unauthorized
personnel to tamper with settings. During CAL MODE, the 4-20 mA output is held at
1.5 mA to prevent alarms or other instrumentation from being affected by calibration
levels.
Calibration of the system may now be performed by appropriately exciting the sensor and
holding the magnet close to the UP/DOWN ZERO or UP/DOWN SPAN controls, as
required to obtain correct readings on the front panel LCD readout. ZERO and SPAN
controls do not interact when the zero adjustment is performed first. The RESET control
is provided to place the ST Series in a UNITY GAIN mode of operation. This returns
the ZERO and SPAN controls to the center of their adjustment range thereby returning
offset and gain values to the same starting point each time UNITY GAIN mode is
entered. This is useful for tracking the sensor's sensitivity, which may deteriorate with
age. If a RESET is applied before calibration, the SPAN gas may be applied and signal
shift observed. When signal shift falls to half the original value of when the sensor was
new, it is approaching time to replace that particular sensor.
A non-volatile memory device provides indefinite battery back-up of calibration values
during power interruptions.

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
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FIGURE 1.1
1.2 SPECIFICATIONS:
1.2.1 SENSOR VOLTAGE (ST350/360 SERIES):
Adjustable Voltage; 2 W Max.
1.2.2 SIGNAL OUTPUT:
4-20 mA into 800 Ohms Max. with 24VDC Power Standard
1.2.3 POWER SUPPLY:
18-30 VDC; 4 W Max.
1.2.4 CALIBRATION RANGE:
ZERO -+15 % of Full Scale
SPAN –Turn UP to GAIN of 2, DOWN to GAIN of 0.5
1.2.5 CALIBRATION RESOLUTION:
0.1% of Full Scale

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
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1.2.6 ACCURACY:
±0.1% of Full Scale ±1 Count
1.2.7 AMBIENT TEMPERATURE RANGE:
-40 to +60 °C
1.2.8 TEMPERATURE DRIFT:
Less than 0.1% /°C over Ambient Temperature range.
1.2.9 HOUSING:
Explosion Proof Class 1, Groups B, C, D & Class 2, Groups E, F, G with CSA and FM
approval.

Armstrong Monitoring Corporation
Model ST Series Non-Intrusive Transmitter
-7-
SECTION II
INSTALLATION
2.1 MOUNTING:
The ST Series is packaged in an explosion-proof housing with two 3/4 inch N.P.T.
conduit hubs located in line and across the housing from each other (see figure 8.1). This
housing has symmetrical mounting holes for the electronics, which are drilled so the
conduit hubs may be oriented across the bottom, top, left side or right side. Simply
mount the housing as desired then remove the four screws which hold the ST Series I/O
printed circuit board in place. Orient the I/O PCB so the LCD readout will align properly
and replace the mounting screws.
Note: To gain access to the I/O PCB for wiring or mounting purposes, loosen the
two captive thumb screws in the ST Series front panel and remove the
PANEL/CPU PCB assembly as far as is allowed by the ribbon cable. The front
panel and attached PCB may then be removed from the ST Series housing leaving
the I/O PCB fully exposed. To replace the front panel assembly, align the two
thumb-screws with their mating stand-offs and firmly hand tighten. Be sure the
front panel is centered in the ST Series housing opening.
2.2 ELECTRICAL CONNECTIONS:
Please see the above note for instructions how to access the ST Series I/O terminals for
field wiring.
The ST Series is a three-wire device. There is a positive 24VDC power wire (other
power supplies are available by special order), and a positive output signal wire which is
typically 4-20 mA. The third wire is the system common and serves as power supply and
signal returns. These three wires connect to the three point terminal block labeled TB2.
An earth ground lug inside the explosion-proof enclosure is provided for earth grounding
of shield wires if the three-wire cable is shielded.