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Actually VFD normally used in secondary pump but in some diagram it shows in primary pump so Please clarify what is role of VFD in chilled water system and where it used?
It is used in secondary chilled water pumps which circulates water to AHUs, FCUs, FAHUs or other building air conditioning equipment like CCUs.
The purpose of the VFD installed on secondary chilled water pump/motor is to increase or decrease the speed of motor in order to control(increase or decrease) water flow rate. This increase or decrese in motor speed and accodingly flow rate is governed by means of pressure sensors(pressure transducers).
VFD is normally installed where we have got 2 way modulating valves on chilled water system instead of 3 way valves. In three way valve system, by pass line is available to cater the flow during no cooling load. Whereas on a two way valve, when the valve is fully or partially closes, the water pressure increase which is sensed by pressure sensors which give signal to VFD to reduce the speed of motor and flow rate is reduced and vice versa.
The purpose of the VFD installed on secondary chilled water pump/motor is to increase or decrease the speed of motor in order to control(increase or decrease) water flow rate. This increase or decrese in motor speed and accodingly flow rate is governed by means of pressure sensors(pressure transducers).
VFD-variable frequency drive for CHW pumps to save energy and n control flow. But not on primary side, for starving flow in chiller, damage to coil due to freezing,staging of chiller is on temperature setpoint and not on demand of chiller, will not save power.
VFD is uses to control the water flow GPM upon required amount.
VFDs are mainly used in the secondary circuits, where we have variable speed secondary pumps, in order to control the flow properly with the need of chilled water. Sometimes, they are used for primary pumps in case we have non-dedicated pumps for chillers (not every chiller has its own primary pump, but a set of pumps with one outlet for chillers) or in case we have multistage chillers (this later case is to be checked).
We could then properly control the system to reduce the primary flow to only what was necessary to meet loads.
VFD is Controlling the chilled water transfer pump motor speed depents up on the load
Process/Mechanical skills.
The purpose of VFD in chilled water system is to control the flow of discharge of the pump.
