I said something earlier about "why would I buy a VS pump + VFD if I can buy a SSP + VFD and achieve the same outcome for considerably less $?". Well, talking to my electrician yesterday, he wasn't very keen on installing a VFD for my 3 phase single speed pump because "the pump wasn't designed to be run at slower speeds". I initially dismissed this (in my head) as some of you guys have been doing this for years but then I read that VS pumps are built differently, with permanent magnet motors. Hmm, so maybe just reducing the power has drawbacks? Why would they design a completely new motor if all they had to do was add a box of tricks that reduced the power?
The pump does not care what speed it runs as long as it is primed. Obviously you can over speed it but not under speed it. I don't run my motor less than 25 hertz (60 Hz in USA) on my pool because that is what it needs and my motor always has enough fan cooling. All you need to do is run it fast enough to make sure your skimmers work and if you have a SWG fast enough to generate chlorine.
Pumps are not built differently. The pump does not care what type of motor is driving it. Single speed, dual speed, or VS.
The standard motor can be used on small pool pumps without the insulation class "F" as many are. The static build up frequently written about are in HVAC situations where the motors are constantly ramping up and down for HVAC efficiency HVAC is where the bearing static problems occur. This does not happen in our situation because pool owners with a VFD on a three phase motor don't adjust speed much because we are after slowest speed we can operate to keep the pool equipment functioning properly. Every pool needs a little bit different speed and thus the speed is controlled by adjusting hertz in the VFD. Again, slowest speed means savings on electrical meter. The only time i run wide open is on initial pump start up after maintenance and vacuuming then i slow it down.
The only down side to operating this way is money savings and a quiet pump.
Permanent magnet motors are a bit more efficient than the standard motors, but i cant tell you how much because i don't have one to swap in to measure with an amp clamp.
So again you are back to the three options to save money.
1. buy a like motor and add a VFD
2. buy a new add on motor that has VS included like a V-Green as sold here in the USA.
3. buy a complete new VS pump and motor package to replace you motor and pump. There has to be something sold in your market. Otherwise import one from USA and use a step down transformer. ($$)
By the way what three phase voltage do you have to the pump?