ted spooner

7/28/2019 Ted Spooner

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1

ATRAA Professional Development DayMay 2011

Ted Spooner :

Chair EL42 Co-convenor of TC82 WG3 on Systems

Member of WG6 on Balance of Systems Comp

Standards &

PV Earthing


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STANDARDS - National

AS/NZS5033 revised and will be out for publiccomment mid May. Committee meeting end of July

to discuss comments

AS/NZS4777.1 revised will be out for publiccomment probably June.

AS/NZS4777.2 still being revised.


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STANDARDS- International

MOST IMPORTANT DEVELOPMENTS

International version of 5033 is now out for public

comment internationally.

Inverter safety standard IEC62109-2 will bepublished 2ndhalf of 2011


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Most important short termSAFETY developments

INVERTER SAFETY Standard

Paired with PV Installation Standard


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Inverter safety 62109-2

Protection against electric shock

Floating & Functionally grounded arrays

Additional requirements for stand-alone

inverters

Protection against fire hazards

Inverter backfeed current onto the array

Audible noise

Fault Indication and ALARM

+ many more fine details


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Why do we earth?

To provide bonding of the metal frame of a system toground so that a dangerous voltage is not achieved.

To allow fault currents to flow if an earth fault occurs

somewhere in the system. To provide shielding ie to allow a path for leakage

currents to flow.

To prevent a system floating to a dangerous voltage

that may be undefined.

Where particularly required for equipment or

operational reasons. i.e. Functional Earthing.


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Functional Earthing

+

-

+

-

+

Isolated

Isolated


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Protection against electric shock

IEC Standard - IEC 61140

Protection against electric shock Commonaspects for installation and equipment

&

AS/NZS 3000


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Fundamental rule of protectionagainst electric shock

Hazardous-live-parts shall not be accessible

and accessible conductive parts shall not be

hazardous live

either undernormal conditions with no faultsOR

undersingle-fault conditions


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Protection

under normal conditions is provided by basic

protection.

E.g. Basic insulation, barriers, limitation of Voltage and

or current etc. under single-fault conditionsby fault protection.

E.g. Earthing exposed metal &

Overcurrent protection or other means of detection

Enhanced protective provisions provide protection

under both conditions.

Eg double insulation...Class II.

Provides SAFETYFacilitates Detection

Action taken to removethreat


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InvertersIsolation/separation

Inverters used for grid connected systems

with LV d.c. Inputs are only required to

have simple separation between the a.c

and the d.c sides.

So

A single fault condition can connect the a.c

to the d.c.


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TRANSFORMERLESS

ie non separated

Array grounding -> Ungrounded

Array ground insulation

resistance measurement

Test before Startup

If Fault disconnect andalarm

Array residual current

detection

Either RCD on a.c

Prescribed by inverter manufOr

Leakage detection on array

inside inverter

If Fault- shutdown & alarm


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Functionally Earthed PV Generator

- Resistance Earth connection.

Re > Voc/0.030A

-

+

-

+

Isolated

Isolated

-

+

Isolated

A

N

ERe

1st Fault

2nd

Fault

Earthing of the module frames enables the inverter

to detect module faults. ie detect a first fault.


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+

-

+

Isolated

A

N

EEarth FaultInterrupter

EFIs are not foolproof

1st

Fault

2nd

Fault

What if?


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Earthing

Installation and inverter safety standard

need to be brought into play together as

they have complementary functions to

improve safety.


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QUESTIONS

Let them have it!

I am home in bed.

ted spooner

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