Your scheme may cost the same to run. You need the same number of horsepower-hours regardless of whether you use 1 or 2 motors. With one motor you will save the losses of one motor, but these losses will be replaced by the losses in the accumulator and extra valves.
We really need to see the load profile.
You may benefit from an RMS horsepower survey, if your maximum loading is not more than about 80% over the nominal capacity of one motor/pump set and there are intervening periods of light loading.
For more information on RMS horsepower loading see the Cowern papers.
RMS HORSEPOWER LOADING
There are a great many applications especially in hydraulics and hydraulically-driven machines that have
greatly fluctuating load requirements. In some cases, the peak loads last for relatively short periods
during the normal cycle of the machine. At first glance, it might seem that a motor would have to be
sized to handle the worst part of the load cycle. For example, if a cycle included a period of time where
18 HP is required, then the natural approach would be to utilize a 20 HP motor. A more practical
approach to these types of “duty cycle loads” takes advantage of an electric motor’s ability to handle
substantial overload conditions as long as the period of overload is relatively short compared to the total
time involved in the cycle.
The method of calculating whether or not the motor will be suitable for a particular cycling application is
called the RMS (root mean squared) horsepower loading method. The calculations required to properly
size a motor for this type of application are relatively simple and are presented in this paper.
You may be able to safely overload one motor for short periods of time.
Bill
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"Why not the best?"
Jimmy Carter
