ATS for a PDP to Power Equipments

If you need to transfer the supply without the interruption of load, use make-before-break ATS. It is also called close transition switch. With this type of switch, the second source is connected before the disconnection of the first source. There is a short duration of time (generally in milli-second) when both sources remain connected together. This requires both sources in synch condition, other wise there will be short circuit between the two sources and severe damage will occur. Generally, this type of switch is required for the bypass sources of the industrial or larger size of UPS where the loads are not allowed to be interrupted.

See this thread for further help:

http://cr4.globalspec.com/thread/49698/Automatic-Transfer-Switch

- MS

One thing you are going to have to consider before you put to much effort into using a closed transition switch is acceptance by the utility, they are discouraging the use of them, at least in my area, and require an extensive and sometimes ridiculously cost prohibitive amount of testing before allowing them to be put into service.

There are two type of ATS, (i) Break before Make I.e. open transition (ii) Make before break i.e. close transition Selection of of neutral is also imp like solid neutral,switched neutral or overlapping neutral. Bypass isolation(usually for maintenance purpose) switch can be available with both options and mainly used when thr is critical loads. and difference between close transition and open transition:in close transition you need to have both source available before switching and in open transition mainly it is happens when one source fails and ATS give signals to DG to start.Before transferring from one sources to other you have to take care of in phase switching mainly when loads are motors.