Triconex Training

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Triconex Corporation

System

Grounding

TRICON Hardware

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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.

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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?

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.

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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)

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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

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TRICON TRICON Main Main Chassis Chassis

AC Safety Ground Bar

TRICON TRICON Expansion Expansion Chassis Chassis Each chassis

Each chassis MUST BEMUST BE connected to AC Safety

connected to AC Safety

ground to ensure personnel

safety! safety! TRICON TRICON Expansion Expansion Chassis Chassis

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TRICON

Chassis

AC Safety Ground Bar

Each V5

Each V5 -- V8 Digital I/O V8 Digital I/O Term Panel

Term Panel MUST BEMUST BE connected to AC Safety

connected to AC Safety

ground to ensure personnel

safety!

Digital Input Term

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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

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AC Safety Ground Analog System

AC Safety AC Safety TRICON TRICON Chassis Chassis Isolated +24 Isolated +24 Power Supply Power Supply V+ V+ VV-

-Analog Input Term

Analog Input Term

Once V

Once 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

TRICON Signal Ground

(TSG).

If the TRICON RC Clip is

installed

installed, 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 V TSG V-- is referenced to AC is referenced to AC Safety within

Safety within millivoltsmillivolts range.

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Dedicated Ground Analog System

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

and is completed at the

Main Chassis location

Main Chassis location & any & any remote RXM locations.

remote RXM locations.

The dedicated ground is

typically considered a quiet

earth ground or DCS

Master Reference Ground.

Isolated +24 Isolated +24 Power Supply Power Supply V+ V+ VV- -TRICON TRICON Chassis Chassis

Analog Input Terms

Dedicated Ground

AC Safety

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Dedicated Ground Analog System

AC Safety

Dedicated Ground

Field loop wiring shields

are typically connected to

TRICON Term Panels.

The TRICON Term Panel

shield ground screws

should be tied to

instrument ground or the

dedicated ground. dedicated ground. TRICON TRICON Chassis Chassis Isolated +24 Isolated +24 Power Supply Power Supply V+ V+ VV-

-Analog Input Terms

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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

connected between the signal and chassis ground

#8300A/#8301A/#8305A/#8306A TRICON Power

Modules allows one to disconnect the internal RC

network and directly access the TRICON signal

ground.

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TRIOCN RC network

V9 System

The RC network is external to the TRICON Power

Modules.

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TRIOCN RC network

Stand

Stand--Alone DigitalAlone Digital--Only SystemOnly System

Connecting the RC jumper will be sufficient

Stand

Stand--Alone AnalogAlone Analog--Only or Mixed Only or Mixed Analog/Digital System

Analog/Digital System

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TRIOCN RC network

Integration 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 any MODBUS connections.

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Connecting two pieces of equipment located in Connecting two pieces of equipment located in

different buildings

TRICON I/O bus RSTRICON I/O bus RS--485 connection 485 connection

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, non

not 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.

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Emergency Shutdown (ESD) and Fire & Gas

detection applications very often require the

I/O system to be "floating".

In a floating ground system, the field power

supply is not directly connected to earth

ground , but is connected to an artificial

ground which can be created with a high

ground which can be created with a high-

-impedance resistor voltage divider.

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24VDC POWER SUPPLY UNIT + -24VDC POWER SUPPLY UNIT + -EARTH GROUND TO ETP POWER 24VDC 0VDC R1 R2

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The main use of a floating ground system with a

suitable Ground Fault Detector allows for the

implementation of a "no

implementation of a "no--fail system".fail system".

A “no

A “no--fail system” is faultfail system” is fault--tolerant of any tolerant of any singlesingle field

field--wiring fault to earth ground.wiring fault to earth ground.

These ground faults should be detectable by

the GFD, and if repaired in a timely manner, a

shutdown or disturbance to the application

should be avoided.

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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

earth ground, other than that of the fixed

high

high--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.

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The HOLEC GFD has a sensitivity of 20mA

minimum (between +

minimum (between +veve and and --veve), when used with ), when used with

an external 1.2k

Ω

resistor divider in 24VDC resistor divider in 24VDC

applications. applications. 24VDC POWER SUPPLY UNIT + -24VDC POWER SUPPLY UNIT + -EARTH GROUND HOLEC + -R1 R2

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It is common to install multiple

It is common to install multiple GFDsGFDs in a in a

system, either one per Marshalling

Cabinet or one per termination panel.

After a ground fault has been detected,

only the field wiring of the points

attached to the alarmed GFD needs to be

searched for the earth short.

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Ground Fault Detection with D.I. Module

EARTH GROUND R1 R2 HOLEC 24VDC 0VDC PS+ PS-+ -DI ETP DI MODULE

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The following limitations apply to the use

of

of 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 negative side of the contact when the

contact is closed. When the contact is

open, the GFD might not detect the fault.

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When the contact is open, the impedance When the contact is open, the impedance

of the input circuitry 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

might not detect the fault.

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Ground Fault Detection with D.O. Module

EARTH GROUND R1 R2 HOLEC 24VDC 0VDC PS+ PS- + -DO ETP FROM DO MODULE

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The following limitations apply to the use

of

of GFDsGFDs with digital outputs:with digital outputs:

the negative side of the load.

the positive side of the load when the

load is energized. When de

load is energized. When de--energized, a energized, a

GFD might not detect the fault.

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When deWhen de--energized, the impedance of the energized, the impedance of the

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

might not detect the fault.

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Ground Fault Detection with A.I. Module

EARTH GROUND R1 R2 HOLEC 24VDC 0VDC PS+ PS-+ -AI ETP Tx 250 180

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Ground Fault Detection with A.I. Module

From test results and the electrical

circuit analysis, we confirmed that the

accuracy degradation in the presence of a

ground fault is inherent in any 4

ground fault is inherent in any 4--20mA 20mA

instumentation

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TRICONEX

Your supplier for all

your Safety and Critical

Control Needs

Defects

Down Time

False Trips

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BACKPLANE 8-POINT ANALOG OUTPUT MODULE

P WRA (22A) RTN (22E) P WRB (24A) CABLE Selector Logic DAC TERMINATION PANEL RTN (24E) OUT1 (2A) RTN1 (2E) Selector Logic DAC Selector Logic DAC Loop powe r Curre nt loopba ck Curre nt loopba ck Curre nt loopba ck A B C

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32-POINT ANALOG INPUT MODULES BACKPLANE CABLE to s pa re TERMINATION PANEL

Is ola tion/filte ring

ADC Amp 1 32 Mux Hi-Ref Low-Re f ADC Amp 1 32 Mux Hi-Ref Low-Re f ADC Amp 1 32 Mux Hi-Ref Low-Re f P S 1 P S 2 P S 1 P S 2 to othe r points 180 ohms Note 3

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Types of Power Utility Power Mains Power UPS Clean Floating AC / DC

Types of Earth Connection

Clean Earth Dirty Earth Utility Earth Low noise System Computer

Basically on two types of Ground :-a) AC - dirty b) DC - clean System earth Instrument earth EMC Electromagnetic Compatibility

-> Started by the military application 15 yrs ago

Use 3 core power cables for optimal line filtering

Power source is reference to earth

Floating power contains much more noise than earth reference Floating power needs isolation transformer

Floating power may drift to any common mode potential Line filtering requires earth connection

Impedance if 3 core power is 100 ohms I/A designed by National Electrical Code

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Normal and Common mode signals by : potential equalisation

Galvanic isolation Shielding

Enclosures

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GROUNDING the TRICON GROUNDING the TRICON

Expansion Chassis

(Protective Earth)

AC SAFETY GROUND

1/4" Bolt on left side of each chassis Main Chassis

Expansion Chassis

AC Safety Ground