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Posted By Topic: How to calculate voltage rise

Oct 08 2019 09:58

EWRB doesn't have AS/NZS 4777.1 2016 available under there subscription so I was just wondering if anyone could advise me on how it's done? Is it just basically the same as voltage drop?

I understand we are required to work to the cited AS 4777.1 2005 which doesn't say anything about voltage rise but would like to know regardless

Oct 08 2019 10:11

Yes it's just voltage drop in reverse.

2% maximum rise between the point of supply and the inverter a.c. terminals. Calculated at the rated current of the inverter.


Oct 08 2019 10:16

4777.1 is $128+gst

Might be a good investment. But it looks like only the 2016 version is available on the site.

Oct 08 2019 11:28

Because SNZ does not hold copyright in any AS Standards (eg AS 4777.1: 2005 as cited by Schedule 2 of ESRs); they can't be included in the deal arranged between SNZ & EWRB.

The later edition, which is joint AS/NZS, has not yet been cited by ESRs so is not part of the deal.

The point of the rule about voltage rise is that we don't want people cranking up the output voltage of the inverter in order to counteract the voltage sag that occurs when excessive load is applied to an under-sized inverter; because once the load returns to design levels the output voltage would be excessive.
a) we don't want appliances to be subjected to excessive voltage; and
b) we don't want detrimental effects on the network voltage; which networks are required to maintain within prescribed limits.

Oct 08 2019 11:50

An important addition to the above points, and the most critical, is the overvoltage shutdown of the inverter if the output voltage control of the inverter goes faulty.

Oct 08 2019 14:28

I do have a copy of the cited AS 4777.1 2005, I was quite surprised how little was in it but I guess at the time that was all that was deemed needed

And like I said, although it may not be something directly cited or mandatory volt rise was just something I wanted to be aware of because obviously it's still a very real thing

That's interesting AlecK, why is it that the newer versions of other uncited standards are available then? Such as 3000, 5033 and 3010

Is this because they are updates of AS/NZS standards where 4777.1 2016 is the first AS/NZS version?

Oct 08 2019 16:45

The original deal was restricted to the standards cited in ESRs (Schedule 2), but limited to only those SNZ held copyright.

Later, after a LOT of pressure, a few others were added, eg 3008 for cable selection, and 3017 for how-to-test; on grounds they may not be directly cited in ESRs but they are still absolutely necessary.

I guess once a Standard is on the list, SNZ's system just keeps allowing access to amendments and revisions as they come available. But for 4777, someone will have to make a change to the "subscription" list to include it.


Oct 08 2019 19:42

Ah, right, understood

Just interesting how part 2 of 4777 is available but part 1 isn't, guess it's just the way it is

Still very lucky to have access to the ones we do regardless, seems so silly in Australia they have to pay for them all, doesn't encourage people to want to use them and comply