Motor Protection Settings:- Thermal Time Constants in REM 615

Basically, the first three you gave match in respective order the second three.

but setting the Thermal time constant start= 9min (540 s) will result in tripping since the starting current = 6 x In and starting time is 31 Sec, according to trip curve given in technical reference manual of REM 615

How did the phone call to the motor manufacturer go?

Try the above settings.

In my opinion 9 min it is rotor locked [short-circuit]thermal constant, 25 min it is for overload estimation temperature and 175 it is for cooling -in standstill position-if two or more startings are involved.

If motor parts are heating the temperature rise is : DT=Tconductor-Tambiant=Tinf*(1-exp(-t/Tk).

For instance, if stall time[from the motor catalogue] is t=10sec and maximum DT=130-40 [for class F insulation and 40 dgr.C ambient] then Tinf1=90/(1-exp(-10/60/9))=4905 dgr.C[if the motor will stay in locked rotor position infinite time!]Then for 5 sec start time DT=4905*(1-exp(-5/60/9))=45.2 dgr.C.

If we want to know what could be the temperature when the motor is stopped and not energized after t3 sec. DT=Tload*(exp(-t3/Tk3) If Tload=Trated=90 and t3=1 min then DT=90*exp(-10/175)=85.

In usually load condition[rated]Tinf2 has to be 90[130-40] then for an overload of x% Tinf2x%=Tinf2*(1+x%/100)^2 and DTx%= Tinf2x%*(1-exp(t2/Tk2)). For instance x%=30,t2=1 min.

DT30%=90+90*(1.3)^2*1-exp(-1/25))=96 dgr.C

See also:

https://www.selinc.com/WorkArea/DownloadAsset.aspx?id=3690