×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Battery Storage inverter not earhted on AC side

Battery Storage inverter not earhted on AC side

Battery Storage inverter not earhted on AC side

(OP)
Hi,
I came across a design in which a grid tie inverter (110kVA at 415V) is connected to Battery system on DC side. On the AC side the inverter is connected via separate isolation transformer (delta -star). delta on inverter end and Star on utility end. Hence the inverter AC side is ungrounded. If there any minimum requirement stipulated by any standard if any type protection is required between inverter and the isolation transformer. The cable run between between the transformer and inverter is 10m.

RE: Battery Storage inverter not earhted on AC side

Its quite difficult to advise on any relevant standards without knowing a location, however, I'd expect some sort of legislative requirement to be able to appropriately be able to detect and clear faults, which would include the ungrounded section of the installation. From where I am I know the utility took a very strong stance on not having appropriate protection on ungrounded schemes, but results may vary on location.

There are obviously varying ways to achieve this, its also usually a lot easier with a grounded system and some sort of current protection, but not impossible with an ungrounded scheme. An insulation monitoring scheme might be able to be used. Depending on the level of isolation on the DC bus to the AC stage, a DC ground fault system may also pick up inadvertent grounding on the AC side.

RE: Battery Storage inverter not earhted on AC side

Quote (In Canada;)

(2) Wiring systems supplied by an ungrounded supply shall be equipped with a suitable ground fault detection
device to indicate the presence of a ground fault.
(3) Ground fault indication activated by the ground fault detection device required by Subrule (2) shall be
clearly
(a) labelled as to its purpose; and
(b) visible to persons monitoring the status of the system.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Battery Storage inverter not earhted on AC side

I'm more used to seeing both inverter and transformer in a single, listed, package. Then it's all up to the testing lab to determine if everything is taken care of. I wouldn't be surprised to find that your inverter can do its own ground fault detection.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources