4 Pole Isolator

In one of our Distrubution Board DB, We are using 04-Pole --63 Ampere Isolator

Can We use -03 Pole Isolator With Neutral Link Short,Plz justify

<sigh> Is this a homework question?

Are you switching the neutral (or using it as a control contact) at the moment with the 4th pole? If so then chances are (and local electrical regulations (country and state specific) likely dictate) that you need to switch the neutral, so no you cannot use a 3 pole isolator with a solid neutral link.

If the 4th pole is currently not being used (ie- you are only switching three phase no neutral), then you can use a 3 pole isolator BUT ONLY if you are allowed to make the design substitution from a 4 pole to a 3 pole isolator.

For more clarification consult a more experienced co-worker/manager/student/lecturer.

Yes you can, if your supply authority permits the neutral link.. Technical I don't see any problem except you will not have switched neutral & this point be kept in mind during maitenance as neutral current may pass through the neutral link.

Ramesh

Is the Isolator an Incoming One or an Outgoing Feeder? If Incoming and if this DB is also fed from another stand-by source such as a DG set, then use of 4-Pole Isolator is strongly recommended. Otherwise need not.

Yes,you can use 3 Pole isolator if you have only one source of power available,this will cut yr cost of using 4 Pole.But if personnel hv to carry out maintenance or any form of work along this circuit switched by this 3 pole isolator,then you may hv to use a 4 pole isolator for the purpose of safety of life frm any leakage or fault current that may occur or pass thru the linked neutral point/terminal.

No you cannot use a 3 pole isolator if u have more than one source(ie Utility source and Generator source or any other form of Standby or emergency source).U must use a 4 pole isolator to completely break the three phase and neutral of one source from interfaring with three phase and neutral of another source.Conclusively,if u hv a 4 pole main isolator or 4 pole change-over board or switchgear at yr source incomer,which is VERY IMPORTANT,then u are free to use 3 pole at yr sub circuit distribution boards.

Patrick Whowha