Automatic Transfer Switch

Regards.

A GA.

Let me add to your comments on UPS'

I recommend this switch should be a 2-HAND_OPERATED_SWITCH which actually disconnects the Critical-Load from power only then the "Forced-Tranfer" switch can be operated. Both switches are so Interlocked that Power-Transfer switch can not be operated.

Have a fine day !

A GA for good Answer.

I would like to add that in rotary-MBB-switches there are the type that the rorary contact is extended on the side to keep contact with the previos fixed-conct while making to the next position fixed-contact; & in BBM switches it is very short to ensure that it breaks from the previous fixed point well before it makes to the next fixed contact.

Regards.

Thanks for the information. I have paralleling switchgear with synchronizing panel as well complete with relay protections. I used ASCO paralleling switchgear with redundant master control for the paralleling of the generators. Have you used ASCO paralleling switchgear? Which is better, Zenith Energy Commander by G.E. or ASCO? and why?

There is a BIG difference in application however. Closed Transition ATSs are for parallelling or load sharing, peaking etc. If the ATS is there for emergency backup power, i.e. in the event of a utility power failure, a Closed Transition switch may not only be dangerous, it may be illegal. If the utility power is off, during that brief moment that the switches are all closed the standby generator will be (or trying to be) powering the entire connected grid. This is especially bad if a linesman happens to be working on the utility lines when the ATS closes!

Regards.

Good comments

In our country I do not know if local Power-stations have any Emergency-Generators to connect to Grids; [some setups have their personal but do not connect to grid].

Linemen keep the keys of of the switch gear feeder on which they are working & put a Shrt-Circuit cables on the power line near their place of work.

To reinforce what JRaef has said...

The use of a closed tranisition transfer switch in a "classic" emergency power feed setup to provide power to an installation or a part of an installation is not legal in Canada. CEC rule 6-106 talks to this issue.

Dear Mr. Marjohr,

Asco manufactures ATS upto 4000A in ASCO 7000 series. - www.asco.com which is a part of Emerson group. you may please ask their representative. There is 1 more terminology- overlapping neutral. Please confirm whether this is used for closed transition ATS.

Dear Mr. shanbhag,

exactly, I'm planning to use ASCO 7000 series ATS. I have a question, which do you prefer for a 4 pole ATS? a switched neutral ATS or overlapping neutral? what are the difference between these two?

Dear Mr. Marjohr,

This is the only point where i have a bit of confusion. The fact is that ASCO ATS is a sort of proprietory product(sorry , if am wrong) and since the technicalities of this product is being defined by ASCO, you need to ask their rep only. May be, bothe switched and overlapping may be the same condition, only terminology varies.

ASCO has one more version in ASCO7000 series i.e. with bypass maintenance facility. but it is twice costly compared to normal ATS. Please visit their site www.asco.com or google search emerson power.

Regards

Thank you mr. shabhag. I appreciate your help.

Dear Gents,

Thank you for all the information that you gave. I really appreciated it. I prefer to use closed transition ATS since I have a huge critical load to support (IT loads). What I know, closed transition will be operating just like the open transition once the power from the utility fails and transfer to the generators via ATS. The difference between the open and close transition is when if the utility power is back, the closed transition will operate as make before break. it will synch with the utility power before it breaks with the emergency generator power. Is this correct or I misunderstood something?