We are currently using your T200 Thrusters in a custom-built ROV system, where each T200 is operated as a vertical thruster. Our setup includes:
4x T200 thrusters (vertical)
30A ESCs for each T200
Power Supply: 16.5V DC
ROV weight in air: 35 kg
Recently, we encountered a serious issue with one of the T200 thrusters: the stator core appears to have cracked. We would like to understand more about this issue:
Possible Cause:
What could cause the stator core to crack under normal ROV operation? Could this be due to overcurrent, vibration, or mechanical stress?
Repair Guidance:
Is there any recommended method or guideline to repair or replace the stator? Or is complete thruster replacement necessary in such cases?
Electrical Parameters:
We are currently running the thruster at 16.5V DC using a 30A ESC. Is this within the safe operating range? If not, what are the ideal current and voltage specifications for long-term reliable operation?
Preventive Suggestions
Are there any measures we can take to prevent this issue in our other thrusters (e.g., current limiting, better mounting, dampening)?
Material & Structural Inquiry
What material is used in the T200 stator core, and is there any known history of fatigue or cracking in similar cases?
Are there any batch-specific manufacturing issues that may apply to the unit we received?
Environmental Considerations:
Could pressure at depth, temperature changes, or corrosion be contributing to the stator damage?
Is the T200 rated for long-term vertical thrust usage under semi-static load (such as maintaining hover)?
Vibration & Mounting Feedback
We mount the thruster directly to the ROV frame. Could vibration feedback or frame resonance be contributing to mechanical stress on the stator?
Warranty or RMA Possibility:
Is the stator cracking covered under warranty or a return/replacement policy?
If not, can we purchase replacement stator or internal parts for in-house repair?
Hi @tony-white
We want a solution for our issues that has been held. Including the reasons and all which we have mentioned above in the query. In place of replacement could you please look after it and tell us what can be the cause and possible solutions for this?
Hi @AnkitPandia -
This is a known issue that can crop up from time to time. It’s typically related to operating in very hot or cold water, at high power output, which can cause rapid expansion/contraction of the stator leading to cracking and subsequent failure.
The only solution is to replace the stator!
Please use the contact form to reach out.
Cracked stators generally need to be replaced (rather than repairing with a marine epoxy), as the stator windings will corrode if exposed to salty water (which is not reversible), and any potential patch-ups would need to be smooth with the existing stator surface to avoid rubbing against the rotor during operation.
If a thruster fails while you are operating within the rated conditions, please let us know, so we can help resolve the issue (potentially sending a relevant replacement if the failure was within the rated operating conditions), and so we can track how and where our products fail, to identify issues in our manufacturing lines, and/or improve the product design in future iterations.
Per the Technical Details section on the T200 product page, 16.5V should be fine, and at that voltage the thruster will not draw more than 30A of current. There may be some concern with your ESC overheating if used continuously without sufficient heat dissipation, but that kind of effect is not captured in power specifications.
Stress fractures and crack propagation are likely the main relevant considerations here, and we provide guidance on care and maintenance, especially with respect to abrasive and corrosive operating conditions.
There is some extra information on longevity and usage in the FAQs on the product page
Beyond that, as Tony mentioned, operating at high current in very hot or cold water can increase the material stresses, especially if there are frequent and rapid cycles between temperatures. If you happen to be in extreme conditions it may be worth having some kind of staging, with the vehicle resting in water before and/or after a dive to slow down the temperature transitions (as has been previously described by a forum user).
Per the revision history on the T200 product page (in the Technical Details section), the only relevant stator change was in 2019:
We do not have any technical bulletins related to T200 stator cracking, so outside of the design change I don’t believe there are any batch-specific issues to be aware of.
See the response to 4.
Vibrations are always a possible contributor to stress, although a plastic frame in water tends to absorb a fair amount of vibration energy, so this is not something we’ve identified as a point of concern. If your custom frame is metal and you’ve strongly screwed the thruster to it then vibrations may be more significant, but even then if it’s significant enough to be a problem it seems more likely that would cause cracks to the stator base rather than the stator itself.
