IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Land Rover with generator and inverter
Topic Summary:
Created On: 11 December 2013 07:26 AM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 11 December 2013 07:26 AM
User is offline View Users Profile Print this message


Avatar for JZN.
JZN

Posts: 562
Joined: 16 November 2006

Hi,

Was doing some work for a commercial customer and they asked me to take a look at a vehicle. They have a landrover with a generator that feeds 110V to a consumer unit with an RCD up front that feeds three double pole MCBs supplying some 100V socket outlets.

Also they have a 12V battery feeding an inverter supplying a 230V socket outlet with RCD.

They've not used the generator or inverter yet. Do they need to earth the vehicle somehow?

Surely if it's sat on the ground on tyres it's not at a proper earth? I was measuring 130volts not 230 with my tester as it measures relative to earth, but if there's not a proper earth......

There's green/yellow straps linking the earth bars on everything to the metal chassis.

Thanks

John.
 11 December 2013 01:29 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11502
Joined: 13 August 2003

Have a read of section 717 - generally where the on-board supply is "earthed" just to the chassis - an electrode to "true" earth may be added where it feeds equipment external to the vehicle, but it doesn't seem to be mandatory.
- Andy.
 11 December 2013 03:04 PM
User is offline View Users Profile Print this message



perspicacious

Posts: 7236
Joined: 18 April 2006

"Was doing some work for a commercial customer and they asked me to take a look at a vehicle. They have a landrover with a generator that feeds 110V to a consumer unit with an RCD up front that feeds three double pole MCBs supplying some 100V socket outlets.
Also they have a 12V battery feeding an inverter supplying a 230V socket outlet with RCD."


I've salvaged 4 DynaWatt units that are 3.5 kVA and 240 V output and as their current limit appears to be 16 A, to get the full output at 110 V, the 240 V was taken directly to a 3 kVA 240/110 V Tx and this output went to a 30 mA RCD and 2 16 A circuit-breakers feeding 2 110 V socket-outlets. They are "in stock" and all I can remember is that one of the "poles" was taken to the chassis but not how

I've managed to fit the "alternator" on my 300 tdi but as usual, yet to get round to finish off fitting the "electronic" box that provides the 240 V at a constant 50 Hz irrespective of engine speed. A bit like the Eberspacher heater on the shelf I had reconditioned to fit ready for the last 6 winters.........

I seem to recall that the new price of the DynaWatt units is over £2k...

Regards

BOD
 11 December 2013 08:09 PM
User is offline View Users Profile Print this message


Avatar for slittle.
slittle

Posts: 3523
Joined: 22 November 2007

We've got a 1kw inverter on our Ranger that comes in handy from time to time.

Generally it only powers drill chargers etc that are sitting on the truck.

I've played around measuring the output to "true earth" and come to the conclusion as it has no reference and all of our chargers are class 2 it's not really an issue.


Stu
 12 December 2013 07:01 AM
User is offline View Users Profile Print this message


Avatar for JZN.
JZN

Posts: 562
Joined: 16 November 2006

What concerns me is that the 30mA RCD needs to be tested. I can't test it if my tester can't see an earth.

Any ideas on how to test this?

John
 12 December 2013 08:48 AM
User is offline View Users Profile Print this message



normcall

Posts: 8134
Joined: 15 January 2005

How about if all the 'earths' are bonded to the chassis, then a test could be done.
Then test again with a floating lead connected to real 'earth' - like have a wheel on a rod laying on tarmac (saw that earlier this year!).

May be a good idea to disconnect the vehicle bits as I suspect electronic equipment today do not appreciate >14vDC up them.

-------------------------
Norman
 12 December 2013 08:57 AM
User is offline View Users Profile Print this message



John Peckham

Posts: 7479
Joined: 23 April 2005

John

I have not tested a vehicle inverter but I have tested loads of generator installations supplying consumer units in food vending trailers. The generators have separated wingdings so need referencing to earth. Check 1st that they are separated with an ohmeter. If they are separated put a link between the neutral supply terminal of the RCD and the earth bar so that you have a neutral rather than 2 poles of the supply. The RCD should then function and you should be able to perform your RCD tests. I would be very wary of performing a high current loop test on an inverter! Try a low current test. You won't need an earth rod as it will have no purpose.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 12 December 2013 09:37 AM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11502
Joined: 13 August 2003

What concerns me is that the 30mA RCD needs to be tested. I can't test it if my tester can't see an earth.

Any ideas on how to test this?

Strictly speaking you just need a loop back to the source's 'star point' (N-PE link on a single phase supply) - it matters not a jot if it's referenced to the planet Earth, some other planet, or just a vehicle chassis (not nothing at all). As John says as long as the N-PE link is there then ADS can operate as normal. Recall that we have circuit-protective-conductors these days, rather than earth wires - precisely because there are some circumstances where they aren't necessarily connected to earth! (another is separated supplies to multiple items of equipment).

- Andy.
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.