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@EdStainless - The turbine blade is 2.25" wide, approx. 1.40" long, and approx. 0.44" max section thickness (at the entering end of the blade). Polishing the blades is an interesting idea, and something we could accomplish without too much additional work. Do you have any detailed...

@Heaviside1925 - Thank you for your reply! I am very confident that the root cause of this material failure is the customer's insistence on operating our torque converter in its reduced pressure mode for prolonged periods, whereas it was intended to operate in the reduced pressure mode for...

Hello All - I am chasing an issue with a torque converter that we use in our mechanical package and I could use some outside advice. The blades in the turbine wheel are exhibiting advanced erosion due to cavitation in the working fluid (ISO VG 32 light turbine oil). The root cause of the...

Thanks all for the advice. Now we have some more ammunition to go back to the customer and hopefully get to the bottom of this. I will follow back if we get any meaningful information from them.

Fortunately (or unfortunately, depending how you look at it), our scope of supply for electrical devices is limited to the motor. The Customer provides the motor starter and any other electrical equipment needed to operate and monitor the motor. So in short, I cannot supply the make and model...

@ waross - Thank you for the insight. I will ask the Customer to confirm how they are measuring the current. The 3kW motor is the driver for our turning gear assembly, and the turning gear is driving a steam turbine + compressor train. Assuming no mechanical issues with the steam turbine or...

@ Parchie - I should have clarified that this is a directly coupled motor, not a belt drive. Our design calculation shows that the load torque is less than the available torque from the motor. The Customer has concluded that the actual load torque is higher than calculated and exceeding the...

Thanks for the additional feedback. Getting information from this customer is very difficult, but we are trying to get more details. The story they gave us is this: the Customer used the 40A locked rotor current from the motor data sheet to set the current limit on their motor starter. When...

@ itsmoked: it also crossed my mind that the motor might be intended for wye connection but was wired delta by the customer. However, the data sheet for the motor states that it is intended for a delta connection. But running with the idea that the motor data sheet is incorrect: if I apply...

@ waross: Is there any condition where a motor can physically pull higher amps than its rated Locked Rotor Current (or Starting Current as they say in IEC world). What the Customer is reporting is that the motor is drawing 70 Amps at startup, while the data sheet for the motor shows that the...

@ xnuke - our Customer suggested that the motor is not strong enough to start the load; however, my understanding is that the motor will not (or cannot?) draw higher amps than the Starting Current (Istart) listed on the data sheet. In other words, my understanding is that the Starting Current...

Hopefully this will be a simple one for you electrical guys: I have a 4-pole 3.0kW motor, 380V/3-ph/50Hz, whose data sheet shows D (delta) connection and starting current of 40 Amps. The Customer reports that when they started the motor, it pulled 70 Amps which consequently caused the motor...

@ mikekilroy: Thanks for the additional thoughts. I understand your concept of over-speeding the motor and increasing the gear ratio accordingly, but our gearbox manufacturer limits us to 1800 RPM maximum input speed (due to the type of seals used on the input shaft). Sorry for the...

@ iop995: Our turning gear system is used both to start-from-rest (breakaway), as well as to catch on the fly during coast down.

Annnnnnd I'm back. Many good questions were asked, and I will try to address all points: Acceleration time to full speed: We do not have a limit, but typically for this type of turning gear the time elapsing from energizing the motor until the driven shaft train gets to full continuous turning...

Sorry again for the radio silence. I'm putting out some other fires at work and I am trying to get back to this ASAP. I have been reading the replies but have not had the time to write my own. Hope to get back to this tonight, thanks for your patience..

I agree that a single electronic component to do the entire job would be ideal. Let me know if I am on the right track: * Connect VFD with sequencing logic in front of 5HP, 1800 RPM AC motor * Set first 'mode' of VFD to run motor at 300 RPM for 1 second My math is: t (sec.) = 2*Theta...

@ MikeHalloran: YES! Just today we were looking at these. It looks like for a given motor hp rating the Flexidyne coupling is rated up to 200% rated torque (max), so it seems we could select our motor such that its 200% torque output is sufficient to achieve breakaway, and any additional...

Wait...I must have missed something here. I guess I'll offer the following: 1) I thought LionelHutz's posts were informative and helpful 2) I thought mikekilroy's posts were informative and helpful 3) If there was a way for me to edit my original post to include all of the relevant details...

^ We currently use TB Woods Sureflex couplings with neoprene (rubber) sleeves, but even then the impact that occurs when the clutch engages can exceed the safe levels for the gearbox. It's just the nature of the beast unfortunately.