I'm working in a High rise building project in Dubai, Our design fire main pump is 1000 gpm(duty + standby) & jockey pump is 26 gpm, head is 20 bar. but fire sub contractor has submitted jockey pump material submittal with 100gpm flow rate. submitted main pump is ok.(capacity & head)

I want to know what is the impact on the system of increasing jockey pump capacity,( of cause kw rating gone up).

Unless you have some regulations, jockey pump just maintains the pressure of a hydrant system when not in use. This is to take care of leakage while the system is pressurised.  

The jockey pump is there so that when little leaks or drops in pressure occur, the main fire pump doesn't start and stop very quickly.  It is there to maintain the pressure in the system.

Typically jockey pumps are low flow and rated for a little higher head than the main pump.

With a higher flow jockey pump, you will likely get a much quicker on/off cycling of the pump.  This will likely cause failure of the pump sooner than with the lower flow pump..

I would reject the submittal and require the specified pump.

According to PEDARRIN2's interpretation, the pump will turn off more quickly. But the number of pump starts will remain the same during the life cycle of the system. So the total working duration of the pump will decrease.
Hence if the new pump working duration in each start/stop cycle would not be very short to prevent full pump running (which depends on the pump start/stop setpoints), it may not have a bad effect on failure rate of the pump.
Also the electric consumption would not be increased due to shorter working time.
Therefor if the pump cost is not a problem, it is reasonable to think on keeping the new pump.

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