NetSafety UNI-TROL Owner's manual

Brand: NetSafety

Model: UNI-TROL

Type: Owner's manual

MODEL: S1G-100-LEL and S2G-100-LEL with PE1100

UNI-TROL GAS CONTROLLER

™

Single-Channel Field Mount Controller with LEL Sensor

REVISED: MAY, 1998

WARRANTY POLICY

The products of Net Safety Monitoring Inc, are carefully designed and manufactured from high

quality components and can be expected to provide many years of trouble free service. Each

product is thoroughly tested, inspected and burned-in prior to shipment. Failures can occur which

are beyond the control of the manufacturer. Failures can be minimized by adhering to the

operating and maintenance instructions herein. W here the absolute greatest of reliability is

required, redundancy should be designed into the system.

Net Safety Monitoring Inc, warrants its sensors and detectors against defective parts and

workmanship for a period of 24 months from date of purchase and other electronic assemblies for

36 months from date of purchase.

No other warranties or liability, expressed or implied, will be honoured by Net Safety

Monitoring Inc.

Contact Net Safety Monitoring Inc. or the authorized distributor for details.

Table of Contents

Unit I - GENERAL INFORMATION

DESCRIPTION ............................................................... 1

FEATURES .................................................................. 1

SPECIFICATIONS ............................................................ 1

Figure 1 - Controller Dimensions in Inches ................................... 2

Figure 2 - Controller Front Panel ........................................... 2

BASIC OPERATION ........................................................... 2

FACEPLATE DESCRIPTION.............................................. 2

OUTPUTS ............................................................ 3

RELAY OUTPUTS ...................................................... 3

RECOMMENDATION .......................................................... 3

CURRENT OUTPUTS ................................................... 3

Figure 3 - Jumper Selections For Isolated or Non-Isolated Current Output . . . . . . . . . . . 4

Table 1 - Current Outputs................................................. 4

PROGRAMMING OPTIONS .................................................... 4

Table 2 - Selectable Output Options ........................................ 5

EXTERNAL RESET ..................................................... 5

AUTOMATIC DIAGNOSTICS AND FAULT IDENTIFICATION . . . . . . . . . . . . . . . . . . . . 5

OPERATING MODES .......................................................... 5

NORMAL OPERATING MODE ............................................ 6

RESET MODE ......................................................... 6

FORCED RESET MODE ................................................. 6

SENSOR REPLACEMENT MODE(SrP) ..................................... 6

SENSOR CALIBRATION MODE(CAL) ...................................... 6

SET-POINT DISPLAY (Spd) .............................................. 7

ADDRESS SET (Adr Set) ................................................. 7

ERROR MESSAGE DISPLAY (ErrChc) ...................................... 7

UNIT II - GENERAL INFORMATION (SENSOR) ............................. 7

DESCRIPTION ......................................................... 7

FEATURES ........................................................... 8

SPECIFICATIONS ...................................................... 8

Figure 4 - Sensor and Transmitter Dimensions ................................ 9

LOWER EXPLOSIVE LIMIT ..................................................... 9

Table 3 - Flammable Gas Volume for 100% LEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

OPERATIONS OVERVIEW .................................................... 10

Table 4 - K Factor for Various Gases....................................... 11

UNIT III - GENERAL INFORMATION (SENSOR)

INSTALLATION .............................................................. 12

SENSOR LOCATIONS ................................................. 12

GENERAL WIRING .................................................... 12

CONTROLLER WIRING ................................................ 13

Figure 5a - Wiring for S1G with Non-Isolated Current Output . . . . . . . . . . . . . . . . . . . . 14

Figure 5b - Wiring for S1G With Isolated Current Output . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 6a - Wiring for S2G with Non-Isolated Output . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 6b - Wiring for S2G With Isolated Current Output . . . . . . . . . . . . . . . . . . . . . . . . 17

DIP SWITCH SETTINGS ...................................................... 18

Figure 7a - Dip Switch Position ........................................... 18

Figure 7b - Dip Switch .................................................. 18

ACTIVE CHANNELS ................................................... 18

CALIBRATION GAS CONCENTRATION ................................... 18

POW ER-UP TIME DELAY ............................................... 19

ALARM SETTINGS .................................................... 19

LATCHING/NON-LATCHING SELECTION .................................. 20

Table of Contents (Cont)

ENERGIZED/DE-ENERGIZED SELECTION ........................................ 21

RELAY SETTINGS ............................................................ 21

Figure 9a - Relay Positions ............................................... 21

Figure 9b - Relay Settings ................................................ 21

Table 5 - Summary of Dip Switch Settings ................................... 22

UNIT IV - SYSTEM OPERATION ........................................... 22

MENU AND FUNCTION SELECTION ............................................. 22

Table 6a - Menu and Function Selection..................................... 22

Table 6b - Main Menu Selection ........................................... 23

Table 7 - Special Function Menu Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

START-UP PROCEDURE ...................................................... 24

MAIN MENU SELECTIONS ..................................................... 24

ERROR CHECK MODE(ERR CHC) ........................................ 24

SET-POINT DISPLAY MODE (SPd) ........................................ 25

Table 8 - System Status Codes............................................ 26

SENSOR CALIBRATION (CAL) .................................................. 27

GENERAL INFORMATION ............................................... 27

CALIBRATION PROCEDURE ............................................ 27

SENSOR REPLACEMENT MODE (SrP) .................................... 28

SPECIAL FUNCTION MENU SELECTIONS ........................................ 29

FORCED CURRENT OUTPUTS (FoP) ..................................... 29

CURRENT CALIBRATION MODE (CuC) .................................... 29

ADDRESS MODE (Adr Set) .............................................. 29

CHANNEL DISPLAY (Chd) ............................................... 29

BYPASS (bPS) ........................................................ 29

OPERATING MODES ......................................................... 30

RESET MODE ......................................................... 30

FORCED RESET MODE ................................................ 30

NORMAL OPERATING MODE ............................................ 30

FORCED DISPLAY (FdP) ................................................ 31

UNIT V - SYSTEM MAINTENANCE

ROUTINE MAINTENANCE ..................................................... 32

MANUAL CHECK OF OUTPUT DEVICES ................................... 32

SYSTEM CHECK IN NORMAL MODE ...................................... 32

SENSOR REPLACEMENT ..................................................... 32

TROUBLESHOOTING ......................................................... 33

REPLACEMENT PARTS ....................................................... 33

DEVICE REPAIR AND RETURN ................................................. 34

Table 10 - Troubleshooting Guide.......................................... 34

-1-

Unit I

GENERAL INFORMATION (CONTROLLER)

DESCRIPTION

TheS1G and S2G Uni-Trol Controller accepts input directly from PE1100 combustible gas

™

sensors. The controller is designed to accept the millivolt signal from the SC1100 LEL sensor

without the need for a transmitter to change the signal to a 4-20mA current signal. Controller

response includes actuation of relays for direct control of field response devices, 4-20mA DC

current output and, a full array of faceplate indicators.

FEATURES

< Controller accepts millivolt inputs (PE1100 LEL sensor).

< Two digital displays, one bar graph display, and high intensity LEDs indicate important

system status information.

< AutoCal feature provides easy and accurate calibration.

< Microprocessor-based controller is easily field programmable.

< 4-20mA current output send important system information to other devices.

< Relay alarm and fault outputs.

SPECIFICATIONS

< Operating Voltage:

24 Volts DC. Device can operate between 18 and 32 Volts DC

< Power Consumption (Controller Only):

3.0 Watts nominal, 5.2 Watts maximum (125 mA nominal, 215 mA maximum at

24 Volts DC).

Maximum startup current is 1.0 Amperes for 5 seconds. Power supplies with fold

back current limiting are not recommended

< Maximum Ripple:

Ripple should not exceed 5 Volts peak-to-peak. The sum of DC plus ripple must

be $18 Volts DC and #32 Volts DC.

< Temperature Range:

Operating: -40ºC to +85ºC (-40ºF to +185ºF)

Storage: -55ºC to +150ºC (-65ºF to +302ºF)

< Relay Contacts:

Form C normally open/normally closed contacts rated for 5 Amperes at 30 Volts

DC/ 250 Volts AC

< Current Outputs:

One 4-20mA DC current, with a maximum external loop resistance of 600S at 18-

32 Volts DC.

< Dimensions:

Refer to Figure 1

-2-

< Shipping Weight (Approximate):

6 lbs. (2.7 kilograms)

< Certification:

CSA certified for hazardous locations, Class 1, Division 1, Groups B, C, and D.

Figure 1 - Controller Dimensions in Inches

Figure 2 - Controller Front Panel

BASIC OPERATION

FACEPLATE DESCRIPTION

The controller faceplate provides LEDs for identifying status conditions, two digital displays and a

bar graph display for indicating the sensor input, and magnetically activated MENU/SET and

SELECT/RESET reed switches (see the appendix for activation instructions) for programming,

calibrating and resetting the system. Refer to Figure 2 for the location of indicators and switches.

< Digital Displays - Two digital displays are used to display the sensor input in both the

Normal and Calibrate Modes; one display indicates the channel and one display indicates

the corresponding sensor input. In the event of a fault, it identifies the nature of the fault

using an alphanumeric code. In the Normal Operating Mode the gas concentration at the

sensor is shown. In other operating modes, the digital displays show the alarm set-points,

programmed calibration gas concentration, output current, or the communication

addresses for the CAN interface. A negative zero drift condition is indicated by a minus

power indicator.

< Bar Graph Display - The common 10-segment bar graph display provides readings of

the sensor input in 5% LEL increments, from 0% to 50% LEL; all 10 segments are

illuminated when 50% LEL is exceeded.

< High Alarm LED (HI) - Flashes in response to a sensor signal that exceeds the high

alarm set-point.

< Low Alarm LED (LOW) - Flashes in response to a sensor signal that exceeds the low

alarm set-point.

< Calibrate LED (CAL) - is illuminated while the controller is in the Calibration Mode.

-3-

< Fault LED (Fault) - is illuminated upon detection of an overall system fault or a channel

related fault.

< Channel LEDs - are illuminated when status on the corresponding channel is displayed

on the common indicators (digital displays and bar graph). During power-up, a channel

LED is on if the channel is selected for operation.

< MENU/SET Reed Switch - is used for changing the menu display resetting the controller

calibration and other system programming and calibration functions.

< SELECT/RESET Reed Switch - is used for menu selection, and other system

programming, for resetting the controller.

OUTPUTS

Relay Outputs:

The relay outputs have SPDT contacts rated for 5 Amperes at 30 Volts DC or 250 Volts AC. The

four relays include an Area 1 low alarm (channel 1), an Area 2 low alarm (channel 2) one common

high alarm, and fault alarm.

RECOMMENDATION

The fault relay output should not be used to activate an automatic shutdown procedure.

The fault output indicates a potential problem with the controller, not an alarm condition.

Current Outputs:

Two 4-20mA DC current output for transmitting system information to other devices are also

included. The current outputs can be wired for isolated or non-isolated operation by changing the

jumpers as shown in Figure 3. Refer to Table 1 for a description of the current output signal

levels.

-4-

Figure 3 - Jumper Selections For Isolated or

Non-isolated Current Output

Current Output Situation

0mA Open or shorted signal output, or loss of power

1mA Fault or Power-Up

2mA Power Fault

3mA Calibration

4mA to 20mA 0 to 100% LEL gas concentration

Table 1 - Current Outputs

-5-

PROGRAMMING OPTIONS

A set of dip-switches, located on the circuit board, can be used to “program” various options and

set-points, including:

< channels selected for operation,

< low and high alarm settings,

< calibration gas concentration,

< power-up delay time (either 45 or 90 seconds),

< latching / non-latching relay action

< energized / de-energized relay action

The alarm relays are programmable for either normally energized or normally de-energized

operation (programmable as a group only, not individually). The fault relay is normally energized.

The low alarm relays are programmable for either latching or non-latching operation. The high

alarm relay is always latching and the fault relay is non-latching. Refer to Table 2.

Jumper selections are provided for normally open or normally closed relay outputs and for isolated

or non-isolated current outputs.

OUTPUT

Selectable Normally

Open/Closed

Selectable Normally

Energized/De-Energized

Selectable

Latching/Non-latching

LOW Y Y Y

HIGH Y Y N

FAULT Y N N

Table 2 - Selectable Output Options

1 Low alarms are programed together, not individually

Programmable together, not individually

High alarm relay is always latching

Fault relay is normally energized

Fault relay is non-latching

EXTERNAL RESET

A normally open, momentary closure switch can be connected between the external reset terminal

and the negative power terminal to provide remote reset capabilities.

AUTOMATIC DIAGNOSTICS AND FAULT IDENTIFICATION

The microprocessor-based controller features self-testing circuitry that continuously checks for

problems that could prevent proper system response. W hen power is applied, the microprocessor

automatically tests memory. In the Normal Operating Mode, it continuously monitors the input

signals from the sensor to ensure proper functioning. In addition, a "watchdog" timer is maintained

to ensure that the program is running correctly. The timer resets the micro-controller if it enters

erroneous processor states within a reasonable period of time.

-6-

If a fault is detected, the Fault LED illuminates, the digital display identifies that a fault has

occurred, the fault relay output becomes de-energized, and the current output drops to less than 1

mA.

The nature of the fault can be identified by a numeric code, which can be viewed in the Fault

Message Display mode.

OPERATING MODES

The controller can operate in any of the modes discussed in this section. Operating modes other

than Normal are selected by activating the appropriate MENU/SET and SELECT/RESET switches

located on the controller front panel. Refer to Figure 2 for a diagram of the controller front panel.

NOTE

This section is intended to acquaint the user with the basic operation of the controller.

Refer to “Unit III” for detailed instructions and description.

Normal Operating Mode:

If no alarms or faults are present, the Module will be in a Level 1 Display Mode; the bar graph and

digital display indicate the sensor inputs. Relay outputs are in their normal state, and the current

output corresponds to the sensor input.

If a low alarm condition occurs, the controller will be in a Level 2 Display Mode; the bar graph and

digital display will display the gas concentration at the sensor. The low alarm LED will flash, the

low alarm relay changes state, and the current output changes to indicate the alarm. If the signal

decreases below the low set-point again, the low alarm relay returns to its normal state if

programmed for non-latching operation and remains unchanged if programmed for latching

operation. The current output returns to normal. The low alarm LED will remain illuminated, but

will no longer flash.

If a high alarm condition occurs, the module will be in a Level 3 Display Mode; the bar graph and

digital display will display the gas concentration at the sensor and the high alarm LED will flash.

Reset Mode:

The system is reset by activating the SELECT/RESET switch located on the front panel of the

controller. (Refer to Figure 2) W hen the SELECT/RESET switch is activated momentarily, all

outputs return to their normal condition if no alarms or faults are present. (basic reset).

Forced Reset Mode:

If the controller receives a signal beyond 100% LEL from the sensor, a reset will not clear the

alarms, even if the channel has returned to levels below the low alarm set point. The error

resulting from this occurrence must be cleared and a forced reset applied. To apply a forced

reset, activate the SELECT/RESET switch for 1 second, the LEDs turn off and the outputs return

to their normal condition. The remote reset performs a forced reset.

NOTE

The remote reset performs a reset function only. It cannot be used for other controller

functions.

Sensor Replacement Mode (SrP):

This mode inhibits all controller outputs to allow replacement of the sensor without removing

power from the controller. Alarm set-points and calibration gas concentration are not affected.

The left display will show ‘SrP’ while in the sensor replace mode. The right display will show the

status of the sensor being replaced (‘NoS’ means no sensor is connected). The fault LED is on

and the fault relay is de-energized. The channel LED will be on for the sensor being replaced.

-7-

All other display features will be inhibited. In order to exit this mode the SELECT/RESET switch

must be activated.

Sensor Calibration Mode (CAL):

The Uni-Trol Controller uses a fully automatic calibration procedure that requires no adjustments

™

by the operator. The controller displays ‘Air’ on the left display and channel status on the right

display while automatically performing the zero adjustments. Next the controller will signal the

user to apply calibration gas by alternating ‘gAS’ and ‘in’ on the left display. When the controller

detects that the gas has been applied to the sensor, the left display will read ‘gAS’. Once the

controller has finished the gain adjustm ents it will alternate ‘Cut’ and ‘gAS’ on the left display,

telling the user that it is time to remove the calibration gas. Upon completion of calibration the

controller will automatically return to normal operating mode, after the gas level has dropped

below 50% of the low alarm setting.

If the operator fails to complete the calibration procedure, if an error in the calibration procedure

occurs, or if a successful calibration cannot be com pleted, the microprocessor will automatically

return to the Normal Operating Mode and continue to use the previous calibration data. A fault

indication will be displayed until a reset occurs. If the microprocessor determines that the sensor

is approaching the end of its useful life, a fault code will indicate this.

W hile in the calibration mode, all controller outputs are inhibited and the ‘Cal’ LED is illuminated.

Set-Point Display (Spd):

In this mode, the digital display sequentially shows the

programmed low and high alarm set-points, calibration gas concentration, and communication

addresses. Each value is displayed for approximately 2 seconds.

Address Set (Adr Set): DO NOT USE THIS FUNCTION

The communication addresses for the CAN bus are set in this mode, which is found in the special

function menu. The MENU/SET and SELECT/RESET switches are used to raise and lower the

address. This mode can only be exited by allowing ten seconds to go by without activating either

switch.

Error Message Display (ErrChc):

The microprocessor-based controller features self-testing circuitry that continuously checks for

problems that could prevent proper system response. As a diagnostic and troubleshooting tool,

identifiable faults are displayed on the digital display, using error codes, during the Error Message

Display Mode. The controller will also display an error message after the last channel in the

cycling routine.

NOTE

If no errors exist, this function is hidden and can not be accessed.

-8-

Unit II

GENERAL INFORMATION (SENSOR)

DESCRIPTION

The Net Safety Monitoring Inc. SC1100 combustible gas sensor head consists of an explosion-

proof enclosure, which contains sensor electronic circuitry. The sensors used are catalytic

oxidation sensors, or pellistors, designed to provide continuous monitoring of combustible gasses

such as methane and butane, etc. in the percent lower explosive limits (LEL). Each sensor is a

matched pair of detector and reference elements which are operated in a Wheatstone Bridge

circuit.

FEATURES

High degree of poison resistance means sensors will maintain their sensitivity over extended

periods of operation.

< Designed and manufactured for low drift over temperature extremes.

SPECIFICATIONS

< Range:

0 to 100% LEL

< Operating Humidity Range:

0 to 100% relative humidity

< Response Time:

Less than 30 seconds to reach 90% of full scale reading with methane (in still air).

< Zero Drift:

Typically less than 2% LEL per month

< Sensor Life:

Operation: 2 to 5 years expected.

Storage: Indefinite

< Calibration Cycle:

60 to 90 Days Groups

< Certification:

CSA certified for hazardous locations,

Class 1, Division 1, Groups B, C, and D.

-9-

Figure 4 - Sensor and Transmitter Dimensions

LOWER EXPLOSIVE LIMIT

A combustible gas is one that will burn when mixed with air (or oxygen) and ignited. The lower

explosive limit (LEL), or lower flammable limit (LFL), of a combustible gas is defined as the

smallest amount of the gas that will support a self-propagating flame when mixed with air and

ignited. In gas detection systems, the amount of gas present is specified in terms of % LEL; 0%

LEL being a combustible gas-free atmosphere and 100% LEL being an atmosphere in which the

gas mix is at its lower explosive limit. The relationship between % LEL and % by volume differs

from gas to gas. Refer to Table 3.

GAS, 100% LEL CONCENTRATION

Hydrogen (H ) 4.0%

Methane (CH ) 5.0%

Ethane (C H ) 3.0%

Ethylene (C H ) 2.7%

512

Pentane (C H ) 1.5%

Propane (C H ) 2.2%

Table 3 -Flammable Gas Volume for 100% LEL

For data on other gases, refer to NFPA 5th Edition 325M.

-10-

The LEL of gas is affected by temperature and pressure. As the temperature increases, the LEL

decreases and hence the explosion hazard increases.

The relationship between LEL and pressure is fairly complex, but at approximately one

atmosphere, a pressure increase usually lowers the LEL. The LEL of a gas is not significantly

affected by the humidity fluctuations normally encountered in the operation of a gas detection

system.

OPERATION OVERVIEW

The sensors used are catalytic oxidation sensors, or pellistors, designed to measure

concentrations of combustible gases in air up to their lower explosive limit. Each sensor is a

matched pair of detector and reference elements which are operated in a Wheatstone Bridge

circuit. The active element, which com prises a coil of platinum wire embedded within a catalytic

bead is capable of oxidizing combustible gases while the inert reference element compensates for

changes in ambient temperature and humidity. The heat generated during oxidation increases the

temperature and resistance of the detector element, producing an out-of-balance signal in the

Wheatstone Bridge circuit proportional to the concentration of combustible gas.

Table 4 lists the theoretical factors by which the signal with a calibration gas should be multiplied

to give the signal for other gases. The following formula may be used:

NOTE

These figures are theoretical, and may differ from sensor to sensor. For best results, the

sensors should be calibrated with the gas they are intended to detect.

Example: For an instrument calibrated with Methane and used to detect Propane.

METHANE

K = 112.0

PROPANE

K = 61.8

Signal shown for 50%LEL Propane is calculated as follows:

Signal = 50% x 61.8 / 112 = 27.6%

-11-

GAS K GAS K GAS K

Acetaldehyde 67.3 n-Decane 36.7 Dimethyl Ether 70

Acetic Acid 60.8 Diethylamine 54.6 Methylethylether 49.3

Acetic Anhydride 51.5 Dimethylamine 64.7 Methylethylketone 46.2

Acetone 57.8 2,3-Dimethylpentane 44.6 Methyl Formate 75

Acetylene 63.6 2,2-Dimethylpropane 44.4 Methylmercaptan 67.9

Alkyl Alcohol 57.1 Dimethylsulphide 48.6 Methylpropionate 57.2

Ammonia 142 1,4-Dioxane 50 Methyl n-propylketone 45.4

n-Amyl Alcohol 36.6 Ethane 75.8 Naphthalene 38.1

Aniline 44.1 Ethyl Acetate 57.4 Nitromethane 64.8

Benzene 45.6 Ethyl Alcohol 81.5 n-Nonane 35.2

Biphenyl 28 Ethylamine 58.9 n-Octane 41.9

1,3-Butadiene 62.5 Ethyl Benzene 39.9 n-Pentane 51.3

n-Butane 65.5 Ethylcyclopentane 44.4 iso-Pentane 51.9

iso-Butane 57.8 Ethylene 79.1 Propane 61.8

Butene-1 50.8 Ethyleneoxide 57.9 n-Propyl Alcohol 52.7

cis-Butene-2 54.2 Diethyl Ether 51.8 n-Propylamine 54.1

trans-Butene-2 56.7 Ethyl Formate 49.5 Propylene 57.7

n-Butyl Alcohol 38.4 Ethylmercaptan 62.8 Propyleneoxide 51.2

iso-Butyl Alcohol 59.2 n-Heptane 43.2 iso-Propylether 48.8

tert-Butyl Alcohol 83.1 n-Hexane 41.2 Propyne 46.5

n-Butyl Benzene 35.2 Hydrazine 50.4 Toluene 45.2

iso-Butyl Benzene 35.8 Hydrogencyanide 53.4 Triethylamine 44.6

n-Butyric Acid 42.5 Hydrogen 85.8 Trimethylamine 54.3

Carbon Disulphide 19.8 Hydrogen Sulphide 45.6 Vinylethylether 46.9

Carbon Monoxide 84.4 Methane 112 o-Xylene 40.1

Carbon Oxysulphide 105 Methyl Acetate 55.6 m-Xylene 43.8

Cyanogen 99.9 Methyl Alcohol 96.2 p-Xylene 43.8

Cyclohexane 46 Methylamine 86.5

Cyclopropane 69.7 Methylcyclohexane 49.4

Table 4 - K Factor for Various Gases

-12-

Unit III

SYSTEM INSTALLATION

INSTALLATION

SENSOR LOCATIONS

Proper location of the sensors is essential for providing maximum protection. The method for

deciding the most effective number and placement of sensors varies depending on the conditions

at the job site. The individual performing the installation must rely on experience, common sense,

and knowledge of plant operations to determine the number of sensors needed and the best

controller locations to protect the area adequately.

The following factors are important and should be considered for every installation:

< Sensors should be located where they are safe from potential sources of contamination.

< Refer to sensor application manuals and follow guidelines for sensor installation.

< Sensors must be accessible for testing and calibration.

< Exposure to excessive heat or vibration can cause premature failure of electronic devices,

and should be avoided if possible.

GENERAL WIRING REQUIREMENTS

NOTE

The wiring procedures in this manual are intended to ensure proper functioning of the

device under normal conditions. However, because of the many variations in wiring codes

and regulations, total compliance to these ordinances cannot be guaranteed. Be certain

that all wiring complies with applicable regulations that relate to the installation of

electrical equipment in a hazardous area. If in doubt, consult a qualified official before

wiring the system.

The use of shielded cable is highly recommended for any signal wires to protect against

interference caused by extraneous electrical 'noise'. This includes power and current outputs;

relay outputs do not require shielded cable. In applications where the wiring cable is installed in

conduit, the conduit must not be used for wiring to other electrical equipment.

NOTE

The S1G and S2G controllers have been certified, as ‘No Seal Required’ since it will not

ignite an explosive atmosphere, under normal operating conditions. Net Safety

Monitoring Inc. does, however, recommend conduit seals to prevent moisture damage.

Since moisture can be detrimental to electronic devices, it is important that moisture not be

allowed to contact the electrical connections of the system. Moisture in the air can become

trapped within sections of conduit. Therefore, the use of conduit seals is recommended to

prevent damage to electrical connections caused by condensation within the conduit.

These seals must be watertight and explosion-proof and should be installed even if they are not

required by local wiring codes. A seal should be located as close to the device as possible. Never

should this seal be located more than 18 inches (46 cm) from the device. When an explosion-

proof installation is required, an additional seal may be needed at any point where the conduit

enters a non-hazardous area. Always observe the requirements of local codes.

-13-

W hen pouring a seal, the use of a fibre dam is required to assure proper formation of the seal.

The seals should never be poured in temperatures that are below freezing, since the water in the

sealing compound will freeze and the compound will not dry properly. Contamination problems

can then result when temperatures rise above the freezing point and the compound thaws.

The shielding of the cable should be stripped back to permit the seal to form around the individual

leads, rather than around the outside of the shield. This will prevent any siphoning action that can

occur through the inside of the shield.

It is recommended that conduit breathers also be used. In some applications, alternate changes in

temperature and barometric pressure can cause 'breathing', which allows the entry and circulation

of moist air throughout the conduit. Joints in the conduit system and its components are seldom

tight enough to prevent this 'breathing'. Moisture in the air can condense at the base of vertical

conduit runs and equipment enclosures, and can build up over a time. This can be detrimental to

electronic devices. To eliminate this condition, explosion-proof drains and breathers should be

installed to bleed off accumulated water automatically.

The maximum distance between the sensor and controller is limited by the resistance of the

connecting wiring, which is a function of the gauge of the wire being used. Three wire, 18 AWG,

shielded cable is recommended. If the recommended wire is used, the sensors may be located

up to 500 feet from the controller.

CAUTION

All terminations between the controller and sensors must be good tight electrical

connections. If proper connections are not made, the voltage monitoring circuit in the

controller will not function properly and the sensors may be damaged or operate

incorrectly.

CONTROLLER WIRING

NOTE

The controller contains semiconductor devices that are susceptible to damage by

electrostatic discharge. An electrostatic charge can build up on the skin and discharge

when an object is touched. Therefore, use caution when handling, taking care not to touch

the terminals or electronic components. For more information on proper handling, refer to

the Appendix.

The sensor direct, Unitrol controllers (S1G and S2G) can be configured for an isolated or non-

isolated current output by changing a jumper on one of the controllers circuit boards (see 6a

Figure 3). Figure 5 and 6 show the terminal configuration for the controllers. Figures 5a and 6a

show the proper wiring of the controller for a non-isolated current output. Figure 5b and 6b show

the proper wiring of the controller for an isolated current output.

NOTE

If local wiring codes permit, and if a ground fault monitoring system is not being used, the

minus side of the DC power source can be connected to chassis (earth) ground.

Alternatively, a 0.47 microfarad, 100 Volt capacitor can be installed between the minus

side of the DC power supply and chassis ground for best immunity against

electromagnetic interference.

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NetSafety UNI-TROL Owner's manual

NetSafety UNI-TROL Owner's manual

NetSafety UNI-TROL Owner's manual

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