Re: [PSES] grounding of output of solar inverter

[Brian Gregory]

 Brian is right;  all NEC rules apply to the installation.  In this case, the 
practical solution could be a sub-panel for the house loads that are served by 
the inverter, but there are several ways it could be done.  You are looking 
inside the inverter (and the inverter safety standard) for the solution.  Look 
outside the box. Colorado Brian

-- Original Message --
From: "Brian O'Connell" <oconne...@tamuracorp.com>
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] grounding of output of solar inverter
Date: Tue, 16 Feb 2016 17:27:37 +

Reference articles 250 and 690 of the NEC (NFPA70). Canada and Mexico code 
similar.

Brian

From: Botjan Glavi [mailto:bostjan.gla...@siq.si] 
Sent: Monday, February 15, 2016 9:05 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] grounding of output of solar inverter

Dear experts,

Is anyone familiar with UL 1741? I am dealing with solar inverter for US 
market. Solar inverter can operate in utility interactive mode (feeding the 
grid) or in a standalone mode where only homeloads are supplied by 
inverter (anti-islanding relays are open, due to problems with the grid). When 
anti-islanding relays are open, I have an issue of grounding the neutral 
conductor of output for homeloads. How can this grounding be achieved? Clause 
19.2 does not allow grounding inside the unit (or I have understood it 
incorrectly and it only prohibits fixed connection) and clause 19.3 requires 
that output is grounded. Below is extract from the standard.
Any idea? I think it is the same issue as with UPS.

19.2 An inverter intended to be utility-interactive shall not have a 
direct/solid electrical connection between any output ac conductor and the 
enclosure.

19.3 Other than as specified in 19.2, each ac output circuit shall have a 
grounded conductor. The ac output circuit conductor to be grounded shall be as 
follows:
a) Single-phase, 2-wire - one conductor.
b) Single-phase, 3-wire - the neutral conductor.
c) Multiphase system having one wire common to all phases - the common 
conductor.
d) Multiphase system in which one phase is used as in item (b) - the neutral 
conductor.

19.4 The conductor specified in 19.3 is to be connected by a bonding jumper 
connected between the grounded conductor and:
a) The enclosure of a metal-enclosed unit, or
b) For a nonmetallic enclosed unit, the metal chassis that is bonded to the 
equipment grounding
conductor or terminal. See 18.2.1.

Thank you for your support.

Best regards,
Bostjan

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Re: [PSES] grounding of output of solar inverter

[Boštjan Glavič]

Brian,

Thank you. I have learned that Neutral is not needed to be disconnected during 
anti-islanding operation. So output conductor (Neutral) remains grounded also 
during stand-alone operation.

Thank you all for your support.

Best regards,
Bostjan

-Original Message-
From: Brian O'Connell [mailto:oconne...@tamuracorp.com] 
Sent: Tuesday, February 16, 2016 6:59 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] grounding of output of solar inverter

Also, should have noted to reference the NDs in UL62109-1, which further 
addresses below requirements, as stuff in North America is (finally) being 
harmonized at both building code and equipment standards levels.

See this:
http://publicaa.ansi.org/sites/apdl/Documents/Standards%20Action/2016-PDFs/SAV4704.pdf

Brian

-Original Message-
From: Brian O'Connell [mailto:oconne...@tamuracorp.com]
Sent: Tuesday, February 16, 2016 9:28 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] grounding of output of solar inverter

Reference articles 250 and 690 of the NEC (NFPA70). Canada and Mexico code 
similar.

Brian

From: Boštjan Glavič [mailto:bostjan.gla...@siq.si]
Sent: Monday, February 15, 2016 9:05 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] grounding of output of solar inverter

Dear experts,

Is anyone familiar with UL 1741? I am dealing with solar inverter for US 
market. Solar inverter can operate in utility interactive mode (feeding the 
grid) or in  a standalone mode where only homeloads are supplied by inverter 
(anti-islanding relays are open, due to problems with the grid). When 
anti-islanding relays are open, I have an issue of grounding the neutral 
conductor of output for homeloads. How can this grounding be achieved? Clause 
19.2 does not allow grounding inside the unit (or I have  understood it 
incorrectly and it only prohibits fixed connection) and clause 19.3 requires 
that output is grounded. Below is extract from the standard.
Any idea? I think it is the same issue as with UPS.

19.2 An inverter intended to be utility-interactive shall not have a 
direct/solid electrical connection between any output ac conductor and the 
enclosure.

19.3 Other than as specified in 19.2, each ac output circuit shall have a 
grounded conductor. The ac output circuit conductor to be grounded shall be as 
follows:
a) Single-phase, 2-wire - one conductor.
b) Single-phase, 3-wire - the neutral conductor.
c) Multiphase system having one wire common to all phases - the common 
conductor.
d) Multiphase system in which one phase is used as in item (b) - the neutral 
conductor.

19.4 The conductor specified in 19.3 is to be connected by a bonding jumper 
connected between the grounded conductor and:
a) The enclosure of a metal-enclosed unit, or
b) For a nonmetallic enclosed unit, the metal chassis that is bonded to the 
equipment grounding conductor or terminal. See 18.2.1.

Thank you for your support.

Best regards,
Bostjan

-

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discussion list. To post a message to the list, send your e-mail to 
<emc-p...@ieee.org>

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This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list

Re: [PSES] grounding of output of solar inverter

[Brian O'Connell]

Also, should have noted to reference the NDs in UL62109-1, which further 
addresses below requirements, as stuff in North America is (finally) being 
harmonized at both building code and equipment standards levels.

See this:
http://publicaa.ansi.org/sites/apdl/Documents/Standards%20Action/2016-PDFs/SAV4704.pdf

Brian

-Original Message-
From: Brian O'Connell [mailto:oconne...@tamuracorp.com] 
Sent: Tuesday, February 16, 2016 9:28 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] grounding of output of solar inverter

Reference articles 250 and 690 of the NEC (NFPA70). Canada and Mexico code 
similar.

Brian

From: Boštjan Glavič [mailto:bostjan.gla...@siq.si] 
Sent: Monday, February 15, 2016 9:05 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] grounding of output of solar inverter

Dear experts,

Is anyone familiar with UL 1741? I am dealing with solar inverter for US 
market. Solar inverter can operate in utility interactive mode (feeding the 
grid) or in  a standalone mode where only homeloads are supplied by inverter 
(anti-islanding relays are open, due to problems with the grid). When 
anti-islanding relays are open, I have an issue of grounding the neutral 
conductor of output for homeloads. How can this grounding be achieved? Clause 
19.2 does not allow grounding inside the unit (or I have  understood it 
incorrectly and it only prohibits fixed connection) and clause 19.3 requires 
that output is grounded. Below is extract from the standard.
Any idea? I think it is the same issue as with UPS.

19.2 An inverter intended to be utility-interactive shall not have a 
direct/solid electrical connection between any output ac conductor and the 
enclosure.

19.3 Other than as specified in 19.2, each ac output circuit shall have a 
grounded conductor. The ac output circuit conductor to be grounded shall be as 
follows:
a) Single-phase, 2-wire - one conductor.
b) Single-phase, 3-wire - the neutral conductor.
c) Multiphase system having one wire common to all phases - the common 
conductor.
d) Multiphase system in which one phase is used as in item (b) - the neutral 
conductor.

19.4 The conductor specified in 19.3 is to be connected by a bonding jumper 
connected between the grounded conductor and:
a) The enclosure of a metal-enclosed unit, or
b) For a nonmetallic enclosed unit, the metal chassis that is bonded to the 
equipment grounding
conductor or terminal. See 18.2.1.

Thank you for your support.

Best regards,
Bostjan

-

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discussion list. To post a message to the list, send your e-mail to 
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Attachments are not permitted but the IEEE PSES Online Communities site at 
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formats), large files, etc.

Website:  http://www.ieee-pses.org/
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Re: [PSES] grounding of output of solar inverter

[Brian O'Connell]

Reference articles 250 and 690 of the NEC (NFPA70). Canada and Mexico code 
similar.

Brian

From: Boštjan Glavič [mailto:bostjan.gla...@siq.si] 
Sent: Monday, February 15, 2016 9:05 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] grounding of output of solar inverter

Dear experts,

Is anyone familiar with UL 1741? I am dealing with solar inverter for US 
market. Solar inverter can operate in utility interactive mode (feeding the 
grid) or in  a standalone mode where only homeloads are supplied by inverter 
(anti-islanding relays are open, due to problems with the grid). When 
anti-islanding relays are open, I have an issue of grounding the neutral 
conductor of output for homeloads. How can this grounding be achieved? Clause 
19.2 does not allow grounding inside the unit (or I have  understood it 
incorrectly and it only prohibits fixed connection) and clause 19.3 requires 
that output is grounded. Below is extract from the standard.
Any idea? I think it is the same issue as with UPS.

19.2 An inverter intended to be utility-interactive shall not have a 
direct/solid electrical connection between any output ac conductor and the 
enclosure.

19.3 Other than as specified in 19.2, each ac output circuit shall have a 
grounded conductor. The ac output circuit conductor to be grounded shall be as 
follows:
a) Single-phase, 2-wire - one conductor.
b) Single-phase, 3-wire - the neutral conductor.
c) Multiphase system having one wire common to all phases - the common 
conductor.
d) Multiphase system in which one phase is used as in item (b) - the neutral 
conductor.

19.4 The conductor specified in 19.3 is to be connected by a bonding jumper 
connected between the grounded conductor and:
a) The enclosure of a metal-enclosed unit, or
b) For a nonmetallic enclosed unit, the metal chassis that is bonded to the 
equipment grounding
conductor or terminal. See 18.2.1.

Thank you for your support.

Best regards,
Bostjan

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
<emc-p...@ieee.org>

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Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
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Jim Bacher:  <j.bac...@ieee.org>
David Heald: <dhe...@gmail.com>

[PSES] grounding of output of solar inverter

[Boštjan Glavič]

Dear experts,

Is anyone familiar with UL 1741? I am dealing with solar inverter for US 
market. Solar inverter can operate in utility interactive mode (feeding the 
grid) or in  a standalone mode where only homeloads are supplied by inverter 
(anti-islanding relays are open, due to problems with the grid). When 
anti-islanding relays are open, I have an issue of grounding the neutral 
conductor of output for homeloads. How can this grounding be achieved? Clause 
19.2 does not allow grounding inside the unit (or I have  understood it 
incorrectly and it only prohibits fixed connection) and clause 19.3 requires 
that output is grounded. Below is extract from the standard.
Any idea? I think it is the same issue as with UPS.

19.2 An inverter intended to be utility-interactive shall not have a 
direct/solid electrical connection between any output ac conductor and the 
enclosure.

19.3 Other than as specified in 19.2, each ac output circuit shall have a 
grounded conductor. The ac output circuit conductor to be grounded shall be as 
follows:
a) Single-phase, 2-wire - one conductor.
b) Single-phase, 3-wire - the neutral conductor.
c) Multiphase system having one wire common to all phases - the common 
conductor.
d) Multiphase system in which one phase is used as in item (b) - the neutral 
conductor.

19.4 The conductor specified in 19.3 is to be connected by a bonding jumper 
connected between the grounded conductor and:
a) The enclosure of a metal-enclosed unit, or
b) For a nonmetallic enclosed unit, the metal chassis that is bonded to the 
equipment grounding
conductor or terminal. See 18.2.1.


Thank you for your support.

Best regards,
Bostjan


-

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discussion list. To post a message to the list, send your e-mail to 


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formats), large files, etc.

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