Daniel Hall - How to mitigate flash hazards in a main switchroom

B Y D A N I E L H A L L H I T E C H E L E C T R I C A L A U T O M A T I O N

How to “Mitigate” Flash Hazards in a Main Switchroom

Objective for this presentation

To share examples of utilizing multiple high level risk controls to minimize flash hazards in a Switchroom to the point that special arc flash PPE is not required for many switching and isolating procedures.

To create a safer work environment for operational and maintenance staff.

Category

4 PPE

Topics to be discussed in this presentation

1. The project 2. The Hazards and Risks in the Main Electrical Switchroom to take into

consideration 3. Planning and engineering philosophy for minimizing the Hazards 4. Outcomes achieved and summarized conclusion

The Project

The Customer: Hanson Construction Materials Location: East Guyong situated half way between Bathurst and Orange NSW. Scope of works included:

Turnkey solution for the supply and installation of a fixed basalt crushing and screening plant with a capacity of 220 TPH. Design, engineering, supply, installation and commissioning LV electrical works including the Process Control System (PCS) and appropriate Switchroom and MCC’s.

1. 2MVA Transformer 2. Switchroom 3. MCC and Control Panels 4. Three Crushers 5. Four Screens 6. Six Feeders 7. Eleven Conveyors 8. Three Luffing and Radial

Stackers 9. Dust Extraction 10. Lighting and general power 11. Automation of plant

The Project

The key equipment:

The Hazards and Risks

Generally Quarrying sites of this size do not have permanent electrical staff onsite A lot of contractors who do work on these sites generally do not do a lot of work on mining sites Therefore the primary hazard area’s the design team considered throughout engineering the Switchroom were as follows:

1. Switching and isolation of Electrical devices.

2. Resetting of overloads. 3. Fault finding and testing.

1. Racking in or out Circuit Breakers. 2. Removing or installing Circuit Breakers. 3. Working on Control circuits with energized

parts. 4. Low Voltage testing and fault finding. 5. Removing panels for inspections and other

activities 6. Testing for Dead

The Hazards and Risks

Examples of activities in a Switchroom which involve Arc Flash Risks

1. Dust 2. Dropping tools 3. Accidental touching 4. Condensation 5. Material failure 6. Corrosion 7. Faulty Installation 8. Over-voltages across narrow

gaps

The Hazards and Risks

Common causes of Arc Flash in a Switchroom

1. Proximity of the worker to the hazard 2. Temperature 3. Time for the circuit to break

The Hazards and Risks

Three main factors which determine the severity of an arc flash

What are your Risks

1. Compliance – Failing the standards and the rules can delay project startup and can result in significant fines

2. Injury/Death – Yourself, your co-workers, outside contractors and other third parties. Between 5 and 10 arc flash incidents happen every day

3. Equipment damage – Costly to repair or replace

4. Plant shutdown – reduced productivity, lost revenues, lost costumers, lost jobs

5. Liability – Lawsuits, higher insurance premiums, out of pocket costs if self insured – a single incident can easily run in excess of $10M

Typical Results from an Arc Flash

Pressure Waves

Copper Vapor: Solid to Vapor Expands by 67,000 times

Molten Metal

Intense Light

Hot Air-Rapid Expansion

Extreme Heat 20,000 °C

Shrapnel

Sound Waves

Planning and Engineering for Minimizing Hazards

Our principle for planning to minimize the hazards was to follow the Hierarchy of Hazard Control

1. Label Equipment & Train Personnel on Good Safety Practices 2. Reduce Available Fault Current 3. Shorten Clearing Time 4. Move People Further Away 5. Redirect Blast Energy 6. Prevent Fault

Methods/Technologies to Reduce Arc-Flash Energy, Protecting Personnel and Equipment

Planning and Engineering for Minimizing Hazards

Both work to Reduce Energy

Planning and Engineering for Minimizing Hazards

Power Engineering Studies Required to move forward

1. Load flow studies 2. Protection coordination studies 3. Arc Flash Analysis 4. Touch and Step Potentials 5. Earthing system design and features

Gain a full understanding of the Fault levels in the installation.

Planning and Engineering for Minimizing Hazards

Begin the Equipment Selection Process

1. Create a working Single Line Diagram from the engineering studies to start designing the MSB

2. Take into consideration the fault levels and Arc Flash Levels at each point

3. Start the design on the MSB considering the area’s at which maintenance and operational staff will need to access

4. Investigate switchboard manufactures who can best offer solutions to our designs and Arc Flash Hazard Reductions.

5. Start adding features and new technology to the MSB to further enhance the safety of the MSB

Planning and Engineering for Minimizing Hazards

Our Selection of the Main Switchboard

Eaton xEnergy Low Voltage Main Distribution

The Reasons for selection 1. Type Tested Switchgear assemblies 2. IP Rated to IP55 3. The xEnergy system is modular and designed

for increasing future requirements 4. The Arc Fault Containment Features available 5. The new Technology of Arc Flash Reduction

Maintenance System available on Main Air Circuit Breakers

6. Cost/ availability and proven product reliability

Planning and Engineering for Minimizing Hazards

Switchboard Features

The xEnergy switchboard system consists of IEC/EN 60439/61439 Type-Tested Function modules which provide compliance with AS3439.1

Arc Fault Containment features: 1. Arc Relief Valve directing gases and

heat to a designated area away from personal

2. Form 3b/4a segregation 3. Internal penetration seals 4. Insulation Arc Barriers 5. Creation of Arc Free Zones through

additional partition walls to allow true segregation to comply with the design

What is ARMS?

Planning and Engineering for Minimizing Hazards

Eaton Air Circuit Breakers Arc Flash Reduction Maintenance System

Switchboard Features

Planning and Engineering for Minimizing Hazards

Switchboard Features

ARMS Technology TM Overview

ARMS is a separate integral analog circuit that when enabled in the Maintenance Mode, ARMS TechnologiesTM provides an accelerated instantaneous trip to reduce arc flash (system can trip as fast as 18ms!)

Local and remote enabling and indication capabilities are provided as well as consideration for Lock-out/Tag-out procedures

Planning and Engineering for Minimizing Hazards

Benefits of the ARMS System

Increased worker safety – when enabled, the Arc flash Reduction Maintenance System provides an accelerated instantaneous trip to reduce arc flash.

Reduction in incident energy levels may allow reduced levels of PPE to be used, offering an improvement to worker comfort and mobility.

When properly applied, the hazard risk category frequently can be lowered multiple categories permitting less PPE.

PPE SHOULD ALWAYS BE THE LAST LINE OF DEFENCE

Planning and Engineering for Minimizing Hazards

Disadvantages of the ARMS System

Time- Current Curves

Coordination is Lost Without ARMS With ARMS Activated

We believe this is a small trade off during

maintenance mode when you know you are

exposing people to a higher level of RISK

Once people are away from the risk and ARMS

is switched off, all normal settings are back in place

Planning and Engineering for Minimizing Hazards

How we implemented the ARMS System

Elements associated with the ARMS system 1. Airlock Room outside the Main Switchroom where the remote ARMS

activation switch is located 2. Remote indication inside Airlock room 3. Motion Detectors inside the Main Switchroom 4. Indication and Alarms through the SCADA System

Airlock Room Segregated from Main

Switchroom

Planning and Engineering for Minimizing Hazards

How we implemented the ARMS System

Remote Switch Activated

ARMS Activated

SCADA Messages and Alarms

Motion Detector Activated

SCADA MESSAGES 1. Remote ARMS switch activated 2. Remote ARMS switch de-activated 3. Personnel in Main Switchroom

SCADA ALARMS 1. Personnel in Main Switchroom

without activating ARMS switch 2. Personnel in Main Switchroom and

no movement detected

Planning and Engineering for Minimizing Hazards

Maintenance Mode Schematic

Remote mounted

switch control

Remote switching and indication via

communications

Remote mounted

indication

Planning and Engineering for Minimizing Hazards

SLD Overview

Layout of Main Switchboard Switchboard WITHOUT ARMS Cabinet Category levels

Planning and Engineering for Minimizing Hazards

CAT 0

CAT 4

CAT 4

CAT 4

CAT 4 CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 4

CAT 0 CAT 0

CAT 0

CAT 0 CAT 0

CAT 0

Layout of Main Switchboard Switchboard WITH ARMS Cabinet Category levels

Planning and Engineering for Minimizing Hazards

CAT 0

CAT 4

CAT 4 CAT 0 CAT 0

CAT 0

CAT 0 CAT 0

CAT 0

CAT 1 CAT 1 CAT 1 CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

CAT 1

Planning and Engineering for Minimizing Hazards

Labelling- ACB WITHOUT ARMS Activated

Labelling- ACB WITH ARMS Activated

Planning and Engineering for Minimizing Hazards

Planning and Engineering for Minimizing Hazards

Eliminate the need for operators to enter the Main Switchroom

The use of Electronic Thermal Overload Protection Devices on all “DOL” equipment allows the operators to reset motors in Overload conditions through

the SCADA system. Magnetic Trips still require an Electrician to attend site and investigate this type

of fault.

We selected the use of the Allen Bradley “E3 Plus” Electronic TOL Devices

The E3 Overload Relay is a multi-function solid-state microprocessor-based electronic overload relay for the protection of squirrel-cage induction motors rated from 0.4…5,000 A

Overload Protection

Planning and Engineering for Minimizing Hazards

E3 Plus Electronic TOL

Magnetic Trips Electrician Required

Thermal Trips Remotely Reset by Operator

through SCADA System

Planning and Engineering for Minimizing Hazards

Eliminate the need for operators to enter the Main Switchroom

Remote Switching of all Circuits 800A and above with a remote switching panel in Air Lock Room outside of the Main Switchroom Eliminates the need for the operator or maintenance staff to put themselves in proximity to the Hazards

Remote Switching

Eliminate the need for operators to enter the Main Switchroom

Planning and Engineering for Minimizing Hazards

Viewing Windows to all access doors to allow condition observation before entry

Break Glass switches to all access doors to Trip the Main Switch and Activate the Fire Suppression System without entering the Main Switchroom

Fire Suppression System Activation will also Trip the Main Switch without entering the Main Switchroom

Switchroom Hazards

Administration for Minimizing Hazards

Protect your Protection settings by sealing them once they are set in accordance to the engineered studies

Administration

Create good maintenance schedules for Plant and Equipment

Training and Education to all Staff Specific training in regards to reading and understanding Arc Flash Labelling. There are still a lot of Electrical Staff out there who do not understand Arc Flash Labelling and the potential energy levels they are about put themselves at Risk to.

Display the Current SLD in the Switchroom showing all protective settings and Arc Flash Levels so that they are always accessible.

Create a culture of safety and assessing Risks.

PPE The Last Defense

Arc Flash PPE labelling installed at all area’s of Risk

Educate staff on PPE requirements

Ensure all PPE is accessible at all times for all locations

Reducing the Hazards will Reduce the level of PPE

The higher the level of PPE required the more Hazards maybe introduced such as Heat Stress, Poor Visibility and Limited Body Movement

Summary

In conclusion to this presentation we have shared examples of utilizing multiple high levels risk controls to minimize flash hazards in a

Switchroom

We have demonstrated through the use of “The Hierarchy of Hazard Control” how we have Eliminated, Substituted, Engineered and

administrated Risk controls We have demonstrated how we have reduced the level of PPE

required to work in and around our Switchboards

Thank You

www.hitechelec.com.au