1. A Case Study: Uninterruptible
Power Supply Installations at Mines
Murray Timpson
27th Electrical Engineering Safety
Seminar (NSW)
8th November 2016

2. Acknowledgements
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1. Various mining companies allowing use of the audit findings
2. Brown B. (2006). System Grounding and Ground Fault Protection Methods for UPS Supplied
Power Systems. Square D Critical Power Competency Center.
3. AS/NZS 60950.1:2015 Information technology equipment – Safety, Part 1: General
requirements
4. AS 62040.1.1:2003 Uninterruptible power systems (UPS), Part 1.2: General and safety
requirements for UPS used in operator access areas
5. AS 62040.1.2:2003 Uninterruptible power systems (UPS), Part 1.2: General and safety
requirements for UPS used in restricted access locations

3. Introduction
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This presentation is a case study of various mine sites (underground and open cut) in which:
1. Issues were identified;
2. Risks evaluated; and
3. Controls recommended.
I hope to share with you:
1. What the audit process entailed; and
2. The hidden dangers around UPS installations.

4. The Audit Process
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Using Safety Bulletin SB17-04 “Uninterruptible power supply (UPS) installations at mines”, the
audit process involved the following.
1. Details of each UPS.
2. Specific original equipment manufacturer requirements.
3. Requirements by the relevant Australian Standards.
4. Installation and wiring.
5. Supplies and transfers.
6. Protection of the supply and output.
7. Drawings and maintenance.
An audit check sheet was created.

7. Issues Identified –
UPS Installation
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1. Most sites had no information available for UPS installed – manuals had to be obtained to
determine OEM requirements (e.g. installation and maintenance).
2. In some cases UPS were that old they were no longer supported – hence information was
limited.
3. Using the OEM manuals the following was noted when reviewing the UPS installation.
• Ventilation requirements
• Earthing and protection requirements
• Safety hazards – e.g. backfeeds and live terminals
• Battery system voltage
• Maintenance requirements (e.g. replacing batteries)
The following shows some of the issues discovered.

8. Issues Identified –
UPS Installation
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The manual noted the following.
• Install requires ventilation and vents not to be
blocked (this unit was installed in a sealed cubicle
with batteries);
• UPS batteries operating at 240VDC;
• Output terminals may be electrically live even
when the UPS is disconnected from the supply;
• Batteries to be replaced every 3 years (this unit
had never been maintained).
Other installation issues.
• No warning labels (refer AS/NZS 4871.1, Section 5
Marking and Labelling)
o Danger 240V;
o Danger Isolate Elsewhere Before Removing
Cover; or
o Supplied from XXX.

9. Issues Identified –
UPS Installation
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The manual noted the following.
• Each battery module operates at 120VDC; and
• Each battery module weighs 50kg – batteries
are to be placed at the bottom for
ergonomics.

10. Issues Identified –
UPS Installation
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Paperweights:
• Two old UPS which are no longer
supported by the OEM sitting in an
office not being used - batteries
were replaced in 2012 but there
was no tags identifying their
status/condition.
Just for heck of it because I can:
• UPS supplying office desktops
serving no real critical function –
UPS not necessary.

11. Issues Identified –
UPS Installation
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Concerning:
• UPS failed or faulted and have just been
bypassed;
• Operating UPS installed on a workbench
with a computer and boxes stored on top.

12. Issues Identified –
UPS Installation
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Other examples…….

13. Issues Identified –
Earthing
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AS/NZS 60950.1, Clause 1.7.2.4: IT Power Distribution Systems –
If the equipment has been designed or, when required, modified for connection to an IT power
distribution system, the equipment installation instructions shall so state.
From the audits undertaken, all UPS identified were designed for solid earth installations
typically stating the following requirements for earthing:
• Grounded outlet; OR
• 2 pole, 3 wire grounded source; OR
• Connected utility; OR
• Nothing at all……

14. Issues Identified –
Earthing
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The following was noted.
• UPS (suitable for solid earth supply only) were installed:
o In underground installations (surface) on IT systems with no isolation
transformers/NERs on the output.
o In Open Cuts on draglines, shovels or associated substations supplied by IT systems.
o In CHPPs supplying hazardous areas (e.g. reclaim tunnels) via an isolation transformer
with centre tapped NER.
• Isolation transformers were also being used on UPS outputs to minimise noise issues (e.g.
on communication systems).

15. Issues Identified –
UPS Protection
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AS/NZS 62040.1.1, Clause 4.5.3: Safety Instructions –
It is necessary to take special precautions to avoid the introduction of hazards when operating,
installing, maintaining, transporting or storing UPS; the manufacturer shall make available the
necessary instructions.
This includes references to the following:
• Battery connections;
• Outlets;
• Reference to national wiring rules;
• Maintenance and installation information; and
• Disconnect devices (backfeed).

16. Issues Identified –
UPS Protection
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The following was noted.
• For both underground and open cuts – some supply circuits to UPS were not earth leakage
protected at all (refer AS/NZS 3000, Clause 4.12.5.2).
• Some circuit breakers supplying UPS were inadequately fault rated (refer to SA99-21 Burns
from incorrectly rated circuit breaker).

17. Issues Identified –
UPS Protection
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The following was noted.
• Older UPS (typically 2003 or earlier) do not have feedback protection. Most UPS audited
were installed permanently and did not contain feedback protection. Warning labels
“Isolate Uninterruptible Power Supply (UPS) Before Working on this Circuit” were not
present at UPS supply circuit breakers.
• Some UPS (particularly older units) do have internal circuit breakers (overload only).

18. Issues Identified –
Wiring Systems
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The following was noted.
• Use of third party bypass switches/panels. Two underground sites had issues with these
bypass panels (supply essential services) causing the UPS output circuit breaker to trip
when the bypass switch was operated.
• Drawings not available for some UPS installations (refer to AS/NZS 3007, Section 15).
• Some installs were adhoc.

19. Issues Identified –
Wiring Systems
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• IP2X issues (refer to AS/NZS 3000, Clause 1.5.4.4) on boards and circuit breakers – including
labelling issues.
• Unsheathed (not enclosed / double insulated) cabling supplying UPS outlets– poor
installation (refer to AS/NZS 3000, Clause 3.10.1.1).

20. Issues Identified –
Wiring Systems
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• Accessibility issues to the board supplying the UPS – less than 1.2m, obstructed and
impeded (refer to AS/NZS 3000, Clause 2.9.2.2).
• Some UPS installations did not have test tags for appliances connected (refer to AS 3760).

21. Issues Identified –
UPS Loads
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• Typically UPS only have overload protection built-in as they rely on the building installation
to provide protection on the supply and UPS output (refer to AS 62040.1.1, Clause 5.6.1).
• Most UPS installations have the incorrect circuit breaker type installed on the UPS output
e.g. Type AC instead of Type A (refer to AS/NZS 3000, Clause 2.6.2.2).
• Some UPS installations also utilise power rails which contain a 10A breaker (overload).
• Some cabinets have appliance leads which aren’t labelled in which there is a risk of an
appliance being connected into the wrong supply (UPS or Non UPS).

22. Issues Identified –
UPS Loads
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• Most UPS audited were designed as “pluggable” (refer to AS 62040.1.1). Pluggable UPS are
a layman design so as to allow installation by the user. The UPS output of these units
cannot be connected via extension leads or permanent wiring.
• UPS installs have had or could have extra load added, in which the UPS run time would be
diminished or possibly unable to supply load.
• UPS were typically not programmed or alarm features utilised.

23. Risks Evaluated
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All issues found were referenced to the relevant Australian Standards, detailing each issue and
recommendations.
Risks were evaluated via a traffic light system:
• Red – immediate safety concern;
• Orange – non compliance requiring attention;
• Yellow – non compliance
These were then discussed with site to ensure clarification.

25. Recommendations
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The following is a summary of recommendations.
1. Obtain advice from an engineer not sales;
2. Verify UPS is designed for IT systems where installed;
3. Verify UPS installation compliance to AS/NZS 3000;
4. Warning signage is in place;
5. In particular for safety critical installations:
• UPS are programmed and alarm indication provided;
• Appliance leads cannot be accidently swapped between UPS or Non UPS supplies;
and
• Verify UPS is correct size for the load and ensure the installation can’t be modified.
6. Use maintenance/bypass switches that are:
• Fit for purpose (e.g. from UPS OEMs);
• Clearly labelled noting operation of each switch position; and
• Lockable
7. Appliances are tested and tagged;
8. Drawings are available and up to date;
9. Review EECP for handling of UPS batteries;
10. UPS are added to CMMS to ensure regular maintenance and replacement of batteries.

26. slamengineering.com.au
A Case Study: Uninterruptible Power Supply
Installations at Mines
Thank you