navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address. Following continuous spam/hack attempts on the forum, "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: vehicle inverter system - earth/neutral  (Read 3988 times)
erbus
Newbie
*
Offline Offline

Posts: 47


« on: December 23, 2010, 08:01:08 PM »

....bit off topic but...,

i was asked to carry out an installation check of an vehicle inverter (230vac) system - impedance loop & rcd tests.

the vehicle is a comms vehicle similar to an outside broadcast unit.
vehicle is 24vdc (neg grounded)
has 12vdc derived from a separate alternator (neg grounded)
and 230vac from a 3kw inverter supplied from the 24vdc.
the 230v goes thru an rcd protected consumer unit and supplies internal lighting and 8 three pin double domestic sockets for various equipment - power supplies, laptops, phones, monitors etc.
the veicle is always grounded to earth via spike when in use.

connected up my installation tester and it immediately thru a paddy because it saw 2 'live' phases on the supply.

have looked thru the latest bs7671 there appears to be problems here.

all the equipment connected to the sockets is domestic ie fused & switched on the 'live' side only as is the consumer unit.

the inverter can be configuered so one phase, 'neutral', can be linked to the inverter earth and hence to vehicle chassis to present the traditional live, neutral & earth.

I have an inverter installation at home and it is installed this way with a single live phase. should it be the same on this vehicle?

i am worried that the currently installation is not as 'safe' as it could be, in addition it is very difficult to carry out the loop & rcd checks..........


Logged
Justme
Hero Member
*****
Offline Offline

Posts: 3560


« Reply #1 on: December 23, 2010, 09:06:54 PM »

My thinking is that the N&E should be bonded. At least then the RCD will work & it will be the same as a house hold system.

If you want to find out about dc & inverter Ac systems in metal framed vehicles I suggest you pop over to http://www.canalworld.net/forums/ & check out the equipment threads. They do also have the extra issue of the water & galvanic corrosion but you will get all the info you need.
Logged

Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
2 x Victron Multiplus II 48/5000/70
Cerbo GX & GX 50 touch
BMV 700
6kva genny
48v 1000ah
Grid Possibly coming soon
erbus
Newbie
*
Offline Offline

Posts: 47


« Reply #2 on: December 23, 2010, 09:28:52 PM »

thanks justme,

problem is there is a bit of ambiguity in regs with this type of installation - either system can be right..

but it has to be correct iaw with best practice from the regs
boats and marine applications have a separate bsxxxx yet again - which is different i'm afraid

there are pros & cons with both but really just want to get the best option for this application.

..my gut instinct is to go the N+E route rather than a pair of floaters......but would prefer the reasoning based on the regs....

ta
Logged
Outtasight
Hero Member
*****
Offline Offline

Posts: 886



WWW
« Reply #3 on: December 23, 2010, 11:33:49 PM »

I believe the difference is whether the AC power is used self-contained inside the vehicle or external to the vehicle.  If it's just used inside the vehicle then I think it's ok to not bond the N&E together as the whole thing will be floating.  The car body is insulated from Earth proper, as it's sitting on four rubber O-Rings Wink.   

If you use the power externally (say, running some sockets in a tent some way from the vehicle), then the same advice as applies to small petrol/diesel generators applies to vehicle inverters - N&E bond and use a ground spike for the Earth and use a RCD.  I believe you can use a small generator without the N&E bond IF the appliance is used very close to the generator (like plugged directly into the outlet socket on the generator) AND it's a double insulated appliance.  I read that from the instructions on a Honda portable generator that has a removable link in the output box to make it either float or be N&E bonded.


Logged

http://solarbodge.blogspot.com/
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
erbus
Newbie
*
Offline Offline

Posts: 47


« Reply #4 on: December 24, 2010, 08:56:31 AM »

...because the vehicle is comms - antennas etc at height - it is always grounded, in fact from experience, if not grounded the computers can do strange things- depending on the weather.

...also, from reading about a bit; its a false assumption, that because a vehicle sits on tyres means its isolated from earth, carbon content in tyres, rain, wet etc.

the biggest problem i can see is that with the current config the 'neutral' line is always live, so changing a light exposes somone to a live terminal, equipment is always live on the neutral side when switched off etc. conversely, keeping the 230vac completely isolated from vehicle is inherantly safer from a distribution point of view around the interior.

...just want to comply as best to the regs inc the test regime....

many thanks
Logged
Justme
Hero Member
*****
Offline Offline

Posts: 3560


« Reply #5 on: December 24, 2010, 11:11:16 AM »

I believe the difference is whether the AC power is used self-contained inside the vehicle or external to the vehicle.  If it's just used inside the vehicle then I think it's ok to not bond the N&E together as the whole thing will be floating.  The car body is insulated from Earth proper, as it's sitting on four rubber O-Rings Wink.   


Till some one bridges those rubber O rings by getting in or out of the vehicle.
Logged

Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
2 x Victron Multiplus II 48/5000/70
Cerbo GX & GX 50 touch
BMV 700
6kva genny
48v 1000ah
Grid Possibly coming soon
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!