Do we need Braking resistor with VFD?

Do I need Braking resistor with VFD?
My application is:
5hp 3 phase induction motor (440vac) driven by 5hp VFD.
Motor drives hydraulic pump
Oil flow additionally controlled by valve installed after the pump.
When motor commanded to stop simultaneously valve closes.
Increase of oil pressure is limited by overload valve.

My 'speculative assumption' is: energy buildup when motor stops/valve closes is being dissipated through oil pressure increase. System inertia is 0 (can it be 0?) since pump can not rotate.
And as conclusion I do not need Brake resistor.

Yet I am not an expert, have minimal experience with VFD … would like to get an opinion.
AndreyG... Welcome to Control Com.
I agree with your thought about the Brake Resistor. I suggest you contact the VFD supplier. The VFD might be configurable so that speed is reduced to zero and then the valve is closed! They might also provide one of their Field-techs, or know of one near your location!
Regards, Phil Corso
thank you for your reply Phil,
I was just thinking about it. Firstly, I was wrong in my description. I said oil flow stop - it will not. Instead oil will be redirected to 'neutral' valve and flow back to holding tank.
Secondly, "VFD might be configurable ..." - no. Instead I will be configuring the VFD. And I question: what if instead of breaking it I will just shut down electrical power and let it run until it stops? My understanding there will be no energy flowing back ...? Is this correct? Is there such an option in VFD to set it's output power to 0?
Ans to Q1: Onlv if the valve is a one-way-valve !
Ans to Q2: I'm familiar with VFD's using torque-control to reduce Water-Hammer, common problem in water-distribution plants. Does your VFD have that feature?
Regarding additional help I can provide the name of an Applications engineer, in the US, who is willing to respond to your dilemma !
Regards, Phil
AndreyG your conclusion is correct, low inertia loads generally don’t need a brake resistor on VFD. Only time you may need one is if you ramp down very quickly, for your application you could coast to stop rather than ramp down.
Imagine you a driving a bicycle with out a break.
If you switch of the power supply to your VFD, is like stopping the pedalling and expecting your bicycle to come to halt !
Inertia & road gradient will play a roll here. Same applies to VFD as well.
Having a friction break is equivalent of having a Dynamic Breaking resistor !
Your motor can be stopped very quickly in case of any emergency situation.
I strongly recommend having a DBR even for small systems, since it will protect the bridge from reaching over voltage during regenerative breaking. Moreover rotating equipment should have the ability to stop immediately in case of emergency !

A braking resistor is often needed with a Variable Frequency Drive (VFD), particularly when the VFD is controlling a motor that's frequently decelerating or overhauling. The braking resistor serves to dissipate excess energy in the DC link when the motor is slowing down.

This excess energy is generated because the motor, acting as a generator, sends energy back to the VFD. If not properly managed, this energy could cause an overvoltage fault.

Hence, a braking resistor becomes vital in applications where rapid deceleration or high inertia loads are present, as it effectively dissipates the regenerated energy as heat, protecting the VFD.

However, not all applications require a braking resistor, it highly depends on the nature of the load and the specific use case.