currently i have several generators that has identical parameter. cause of increasing demand, i will add new generatos with different parameter (capacity, speed and etc) to my power plant. my question is :
1. how we connect the new generator? in the same terminal now or i have to buy new one?my current terminal has enough short circuit capacity.
2. currently i have no grounding in my generators but i have grounding in my trafo (at the same side with generator). from my last study, i have to change my configuration. to limit sc current in generators, i have to install new ngr. how much ngr i must buy?is each of generators must have 1 ngr or just 1 common ngr for all my generators?what is the effect for my protection for both configuration?

hi
where is that power plant you talk about.
regards

Genearlly, you can connect your generators to the existing switchboard provided the latter has the short circuit withstandability for all generators running in parallel or for the maximum number of generators that can run in parallel and the required current rating for the maximum connected load. In addition the existing switchboard should have the required number of spare circuit breakers (or available spare space cubicle) to connect all the generators, one breaker for each generator. Your existing switchboard should have the current rating equal at least to the maximum load demand being supplied. Otherwise, you have to install a new switchboard. In fact your question is a general one as you have to have a phylosophie for running the generators and load sheding strategy in case one or more generators become out of service. You can also install bus section circuit breakers in your switchboard to create some flexibility in your connections. If your generators have kVAR and kW share lines, set the generators operation to swing mode in your calculations otherwise set them in droop mode. With regard to NER, you need one set only and this will be connected to all the generators neutral through a set of contactors in parallel, one contactor per generator. One contactor only should be closed at any one time and the rest open so that you have one generator neutral earth point for the proper operation of your protection. You can buy the NER as one assembly including the contactors and the resistor.