Tri Conex

Triconex CorporationTriconex Corporation

System System GroundingGrounding

TRICON HardwareTRICON Hardware

Electrical systems must be connected to ground in order to: Protect personnel from electric shock.Protect personnel from electric shock. Protect equipment from damage.Protect equipment from damage. Protect the site from lightning damage.Protect the site from lightning damage. Ensure the reliability and electrical integrity of the Ensure the reliability and electrical integrity of the

system.system. To have interference free operationTo have interference free operation

What is Ground?What is Ground? It is a connection to the earth, or to something used It is a connection to the earth, or to something used

in place of the earth.in place of the earth.

Why do we require a ground?Why do we require a ground? The ground is required as it is used to establish and The ground is required as it is used to establish and

maintain the potential of the earth.maintain the potential of the earth.

TRICON System typically utilizes three (3) separate ground references:

AC safety or chassis ground (protective earth ground) - TRICON Chassis Ground

Signal or Instrument (or Master Reference) ground - TRICON Signal Ground (TSG)

Field loop shield ground

AC Safety ground is applied to each chassis Signal or Instrument (or Master Reference)

ground is the field loop power supply return

Field loop shield ground is for referencing instrument loop wiring shields typically to instrument or Master Reference ground

TRICONTRICONMainMain

ChassisChassis

AC Safety Ground Bar

TRICONTRICONExpansionExpansionChassisChassis

Each chassis Each chassis MUST BEMUST BEconnected to AC Safety connected to AC Safety ground to ensure personnel ground to ensure personnel safety!safety!

TRICONTRICONExpansionExpansionChassisChassis

TRICONTRICONChassisChassis

AC Safety Ground BarAC Safety Ground Bar

Each V5 Each V5 -- V8 Digital I/O V8 Digital I/O Term Panel Term Panel MUST BEMUST BEconnected to AC Safety connected to AC Safety ground to ensure personnel ground to ensure personnel safety!safety!

Digital Input TermDigital Input Term

AC Safety Ground MUST be applied to each chassis (Main, Expansion & RXM) regardless of floating or non-floating systems.

AC Safety Ground MUST be applied to each V5 -V8 DI/DO Term Panel. (floating/non-floating) as the V5 - V8 I/O ELCO cables do not have a connecting wire to chassis. Connection to AC Safety Ground for V9 Terms are not required.

AC Safety Ground MUST NOT be applied to AI/AO Term Panels and #3504E.

AC Safety Ground Analog SystemAC Safety Ground Analog System

AC SafetyAC Safety


Isolated +24Isolated +24Power SupplyPower Supply

V+V+ VV--

Analog Input TermAnalog Input Term

Once VOnce V-- is connected to a is connected to a AI/AO Term Panel, it is AI/AO Term Panel, it is connected to the internal connected to the internal TRICON Signal Ground TRICON Signal Ground (TSG).(TSG).

If the TRICON RC Clip is If the TRICON RC Clip is installedinstalled, TSG is connected , TSG is connected to AC Safety Ground via a to AC Safety Ground via a parallel resistor/capacitor parallel resistor/capacitor circuit.circuit.

TSG VTSG V-- is referenced to AC is referenced to AC Safety within Safety within millivoltsmillivoltsrange.range.

Dedicated Ground Analog SystemDedicated Ground Analog System

If the TRICON RC Clip is If the TRICON RC Clip is removed, TSG is removed, TSG is disconnected from AC disconnected from AC Safety Ground. Safety Ground.

TSG TSG MUST BEMUST BE connected connected to a dedicated ground. to a dedicated ground.

One connection is required One connection is required and is completed at the and is completed at the Main Chassis location Main Chassis location & any & any remote RXM locations.remote RXM locations.

The dedicated ground is The dedicated ground is typically considered a quiet typically considered a quiet earth ground or DCS earth ground or DCS Master Reference Ground.Master Reference Ground.


V+V+ VV--TRICONTRICONChassisChassis

Analog Input TermsAnalog Input Terms

Dedicated GroundDedicated Ground

AC SafetyAC Safety

Dedicated Ground Analog SystemDedicated Ground Analog System

AC SafetyAC Safety

Dedicated GroundDedicated Ground

Field loop wiring shields Field loop wiring shields are typically connected to are typically connected to TRICON Term Panels. TRICON Term Panels.

The TRICON Term Panel The TRICON Term Panel shield ground screws shield ground screws should be tied to should be tied to instrument ground or the instrument ground or the dedicated ground. dedicated ground.



V+V+ VV--

Analog Input TermsAnalog Input Terms

TRIOCN RC network TRIOCN RC network

V5 V5 -- V8 SystemV8 System

#8300/#8301/#8305/#8306 TRICON Power #8300/#8301/#8305/#8306 TRICON Power Modules are equipped with a simple RC network Modules are equipped with a simple RC network connected between the signal and chassis groundconnected between the signal and chassis ground

#8300A/#8301A/#8305A/#8306A TRICON Power #8300A/#8301A/#8305A/#8306A TRICON Power Modules allows one to disconnect the internal RC Modules allows one to disconnect the internal RC network and directly access the TRICON signal network and directly access the TRICON signal ground.ground.

TRIOCN RC network TRIOCN RC network

V9 SystemV9 System

The RC network is external to the TRICON Power The RC network is external to the TRICON Power Modules.Modules.

TRIOCN RC networkTRIOCN RC network

StandStand--Alone DigitalAlone Digital--Only SystemOnly System

Connecting the RC jumper will be sufficient

StandStand--Alone AnalogAlone Analog--Only or Mixed Only or Mixed Analog/Digital SystemAnalog/Digital System

Connecting the RC jumper will be sufficient

TRIOCN RC networkTRIOCN RC network

Integration with DCSIntegration with DCS

If TRICON is a stand-alone digital-only system, connection of the RC jumper (at the power module for V5 to V8) is sufficient

If TRICON is a stand-alone analog-only or mixed analog/digital system, a single connection must be made between TRICON signal ground and the common tie point of the DCS signal ground

A TriStation Link with model #410x ICM/EICM may cause a problem if the TriStation PC does not share the safety ground connection as the TRICON.

Exercise caution especially if the TRICON and the DCS are physically separated or reside in separate buildings. The same problem could also occur with any RS232 connection including anyMODBUS connections.

Connecting two pieces of equipment located in Connecting two pieces of equipment located in different buildingsdifferent buildings

TRICON I/O bus RSTRICON I/O bus RS--485 connection 485 connection extended beyond the control room.extended beyond the control room.

Current flow via the Shield ground which is Current flow via the Shield ground which is not held at a constant, nonnot held at a constant, non--varying voltage.varying voltage.

Implementing a floating ground system.Implementing a floating ground system.

In most industrial control systems, the return side In most industrial control systems, the return side of the field power supply is directly connected to of the field power supply is directly connected to earth.earth.

Emergency Shutdown (ESD) and Fire & Gas Emergency Shutdown (ESD) and Fire & Gas detection applications very often require the detection applications very often require the I/O system to be "floating".I/O system to be "floating".

In a floating ground system, the field power In a floating ground system, the field power supply is not directly connected to earth supply is not directly connected to earth ground , but is connected to an artificial ground , but is connected to an artificial ground which can be created with a highground which can be created with a high--impedance resistor voltage divider.impedance resistor voltage divider.

24VDC POWERSUPPLY UNIT

+-


+-

EARTH GROUND

TO ETP POWER

24VDC

0VDCR1

R2

The main use of a floating ground system with a The main use of a floating ground system with a suitable Ground Fault Detector allows for the suitable Ground Fault Detector allows for the implementation of a "noimplementation of a "no--fail system".fail system".

A noA no--fail system is faultfail system is fault--tolerant of any tolerant of any singlesinglefieldfield--wiring fault to earth ground.wiring fault to earth ground.

These ground faults should be detectable by These ground faults should be detectable by the GFD, and if repaired in a timely manner, a the GFD, and if repaired in a timely manner, a shutdown or disturbance to the application shutdown or disturbance to the application should be avoided.should be avoided.

The main purpose of a GFD is to detect the The main purpose of a GFD is to detect the presence of an unintentional connection to presence of an unintentional connection to earth ground, other than that of the fixed earth ground, other than that of the fixed highhigh--impedance connection.impedance connection.

A GFD should provide some means of alarming A GFD should provide some means of alarming upon detecting an ground fault.upon detecting an ground fault.

The HOLEC GFD has a sensitivity of 20mA The HOLEC GFD has a sensitivity of 20mA minimum (between +minimum (between +veve and and --veve), when used with ), when used with an external 1.2kan external 1.2k resistor divider in 24VDC resistor divider in 24VDC applications.applications.


+-


+-

EARTH GROUND

HOLEC

+

-R1

R2

It is common to install multiple It is common to install multiple GFDsGFDs in a in a system, either one per Marshalling system, either one per Marshalling Cabinet or one per termination panel. Cabinet or one per termination panel. After a ground fault has been detected, After a ground fault has been detected, only the field wiring of the points only the field wiring of the points attached to the alarmed GFD needs to be attached to the alarmed GFD needs to be searched for the earth short.searched for the earth short.

Ground Fault Detection with D.I. ModuleGround Fault Detection with D.I. Module

EARTH GROUND

R1

R2

HOLEC

24VDC

0VDC

PS+PS-

+-

DI ETP

DI MODULE


The following limitations apply to the use The following limitations apply to the use ofof GFDsGFDs with digital inputswith digital inputs::

A GFD always detects ground faults on A GFD always detects ground faults on the positive side of the contact.the positive side of the contact.

A GFD always detects ground faults on A GFD always detects ground faults on the negative side of the contact when the the negative side of the contact when the contact is closed. When the contact is contact is closed. When the contact is open, the GFD might not detect the fault.open, the GFD might not detect the fault.


When the contact is open, the impedance When the contact is open, the impedance of the input circuitry is in series with the of the input circuitry is in series with the fault impedance. fault impedance.

If the sum of the impedances exceeds If the sum of the impedances exceeds the sensitivity of the GFD, then the GFD the sensitivity of the GFD, then the GFD might not detect the fault.might not detect the fault.

Ground Fault Detection with D.O. ModuleGround Fault Detection with D.O. Module

EARTH GROUND

R1

R2

HOLEC

24VDC

0VDC

PS+PS-

+-

DO ETP

FROM DOMODULE


The following limitations apply to the use The following limitations apply to the use ofof GFDsGFDs with digital outputs:with digital outputs:

A GFD always detects ground faults on A GFD always detects ground faults on the negative side of the load.the negative side of the load.

A GFD always detects ground faults on A GFD always detects ground faults on the positive side of the load when the the positive side of the load when the load is energized. When deload is energized. When de--energized, a energized, a GFD might not detect the fault.GFD might not detect the fault.


When deWhen de--energized, the impedance of the energized, the impedance of the load is in series with the fault impedance. load is in series with the fault impedance.

If the sum of the impedances exceeds If the sum of the impedances exceeds the sensitivity of the GFD, then the GFD the sensitivity of the GFD, then the GFD might not detect the fault.might not detect the fault.

Ground Fault Detection with A.I. ModuleGround Fault Detection with A.I. Module

EARTH GROUND

R1

R2

HOLEC

24VDC

0VDC

PS+PS-

+-

AI ETP

Tx250

180

Ground Fault Detection with A.I. ModuleGround Fault Detection with A.I. Module

From test results and the electrical From test results and the electrical circuit analysis, we confirmed that the circuit analysis, we confirmed that the accuracy degradation in the presence of a accuracy degradation in the presence of a ground fault is inherent in any 4ground fault is inherent in any 4--20mA 20mA instumentation instumentation loops.loops.

TRICONEXTRICONEXYour supplier for all Your supplier for all

your Safety and Critical your Safety and Critical Control NeedsControl Needs

DefectsDown TimeFalse Trips

BACKPLANE8-POINT ANALOG OUTPUT MODULE

PWRA (22A)

RTN (22E)

PWRB (24A)

CABLE

SelectorLogic

DAC

TERMINATIONPANEL

RTN (24E)

OUT1 (2A)

RTN1 (2E)

SelectorLogic

DAC

SelectorLogic

DAC

Loop power

Currentloopback

Currentloopback

Currentloopback

A

B

C

32-POINT ANALOG INPUT MODULESBACKPLANECABLE

tospa re

TERMINATION PANEL

Is ola tion/filte ring

ADCAmp1

32

Mux

Hi-Ref

Low-Ref

ADCAmp1

32

Mux

Hi-Ref

Low-Ref

ADCAmp1

32

Mux

Hi-Ref

Low-Ref

PS 1

PS 2

PS 1

PS 2

toothe rpoints

180 ohms

Note 3

Types of PowerUtility PowerMains PowerUPSCleanFloatingAC / DC

Types of Earth ConnectionClean EarthDirty EarthUtility EarthLow noiseSystemComputer

Basically on two types ofGround :-a) AC - dirtyb) DC - clean

System earthInstrument earth

EMCElectromagnetic Compatibility-> Started by the military application 15 yrs ago

Use 3 core power cables for optimal line filteringPower source is reference to earthFloating power contains much more noise than earth referenceFloating power needs isolation transformerFloating power may drift to any common mode potential

Line filtering requires earth connectionImpedance if 3 core power is 100 ohms

I/A designed by National Electrical Code

Normal and Common mode signals by : potential equalisationGalvanic isolationShieldingEnclosures

Signal to noise ratio

GROUNDING the TRICONGROUNDING the TRICON

Expansion Chassis

(Protective Earth)

ACSAFETYGROUND

1/4" Bolt on left side of each chassis

Main Chassis

Expansion Chassis

AC Safety GroundBus Bar

Triconex CorporationTRIOCN RC networkTRIOCN RC networkTRIOCN RC networkTRIOCN RC networkGround Fault Detection with D.I. ModuleGround Fault Detection with D.I. ModuleGround Fault Detection with D.I. ModuleGround Fault Detection with D.O. ModuleGround Fault Detection with D.O. ModuleGround Fault Detection with D.O. ModuleGround Fault Detection with A.I. ModuleGround Fault Detection with A.I. Module

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