Online assistance for electrical trade people in New Zealand and Australia Login  |  Register  |   Forgot Password
Assistance for electrical trade people
 

 

 

 


Click here to send Ron a pdf document for publication on this Topic

Documents must be less than 200k in pdf format

Posted By Topic: battery readily isolated

Rhino
Feb 26 2019 11:35

battery readily isolated 3.6.7(4509)- inverter batt switch disconnect right beside two solar controller switch disconnectors all individually going to the battery, labelled multiple DC sources, etc. would that be sufficient as readily or does there need to be one additional main battery isolator
   

AlecK
Feb 26 2019 12:18

Battery isolators and short circuit protection should be as close to the battery as practicable - though for lead-acid types NOT inside the battery compartment, due to risk of explosion.
3004 provides reasonable guidance.
The new battery Standard, AS/NZS 5139, is currently out for Public Comment (closing3 April); and provides more info, including for modern battery types.
   

pluto
Feb 26 2019 13:51

One of the major design features when dealing with DC supply is the fact that the battery has a supply source at end of the battery cable and another at the other end of the battery cable has a charging source.

In some installations, in particular with a large amp capacity charging source requires design which is not in any standard normally available to most electrical workers.

To provide the correct overcurrent protection requires a different thinking, in practice you need a HRC fuse or overcurent device on each end of the cable. Also remember many circuit breakers commonly available are only able to control AC currents only and you need to use DC rated circuit breakers.
   

Rhino
Feb 26 2019 14:50

Is there a requirement to have one additional main batt isolator or is 3 isolators grouped together and labelled correctly adequate to provide isolation of the battery bank.?

Both would be as close to the batt as practical. with either situation ,There is always going to be a part of cable from battery to isolators that will not be protected. One situation may be 500mm the other would be 1metre
   

pluto
Feb 26 2019 16:17

Rhino Feb 26 2019 14:50
Your comments 1
Is there a requirement to have one additional main batt isolator or is 3 isolators grouped together and labelled correctly adequate to provide isolation of the battery bank.?

Both would be as close to the batt as practical. with either situation ,There is always going to be a part of cable from battery to isolators that will not be protected. One situation may be 500mm the other would be 1metre

My comments 1
It would appear that you have two cables to the two battery protective devices and provided the cable between the battery and battery fuse is short AND mechnically protected (battery cabinet is OK) andadditional battery fuse(s) are NOT required.

If the cable from a battery fuse or MCB (rated NOT greater than the battery current rating) is feeding a charging source (rectifier) a fuse at the rectifier end of the cable is also required. Sometimes some good rectifiers have a output fuse and provided that it is below battery cable current rating, is also satisfactory to provide the overcurent protection for the remote end of the battery cable (e.g. NOT the battery fuse end of the cable).