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Jeff With 250 A drive, what is the lowest current it can be used for ? Vendor says 10% i.e. 25 Amps. Muthu www.edison.co.in

Never seen off-line 24x7 IR monitoring of windings. Properly sized space heaters keep the IR values up and you check in periodically. Don't see the point of continuous monitoring. Muthu www.edison.co.in

Thanks, Jeff. The vendor did confirm this Fiji drive does not have that capability of 2 in 1 power output. Muthu www.edison.co.in

Thank you, all. Our supplier is going to ask the drive OEM about this possibility. Muthu www.edison.co.in

Agree with Gr8blu. No standards will specify life of electrical machines since it depends on how they are operated, are maintained etc. I have been repairing machines from 1930s vintage to 2024 and I know where the OEMs are cutting corners to cut costs over the years. Previously the designer's...

Agree it's apples and oranges, but these oranges still had 90+ efficiency, not 50 to 60%. May be using higher efficiency cage motors off-sets whatever additional VFD loss but my clients are switching over to VFD due to utility cost saving, less maintenance headaches and option of variable...

For no-load open shaft testing various motors ranging from 50 HP to 1500 HP with maximum no-load current of 500 Amps at 415 V, 50 HZ, I am planning for to go for VFD. If I buy two identical 250 Amps drives, can I parallel them on the output side for 500 Amps? This gives me an option of using...

In India, I have seen a booming market for VFD's. Many of my clients in traditionally conservative process industries like cement, chemical. steel, sugar, glass making, tyre manufacturers etc are replacing their time tested DC and slipring motors with VFD driven AC motors in the last two...

API 541 table those pressures should be ≤ and not ≥. Muthu www.edison.co.in

jeff, as usual, clear explanation. Muthu www.edison.co.in

Design of electrical machines cooling system is more of an art than science. The only goal of any air/hydrogen (primary coolant) to air/water (secondary coolant) cooling system is to have the machine inlet air/hydrogen temperature under 40 deg C, the limit defined by standards. In air/hydrogen...

Rod 12 pole machine Cons: Less efficient, costlier, bigger footprint, heavier (crane), long lead time. Pros: No gear box. Less noisy. Less wear & tear hence less maintenance cost 4 pole machine Cons: Gear box with efficiency loss. Noisier. More wear & tear hence more maintenance cost. Pros...

Hi Walt Yes, it's a diesel. The client is an IPP and bought this used 6.6 KV generator which we rewound for 11 KV to match his other 11 KV DG sets. Running well for two years now. Rod Unlike 2,4 or even 6 pole, multipolar generators are custom designed and built and the few OEM's may not...

8 MW, 8 pole open ventilated generator rewound (6.6 KV to 11 KV conversion) in our shop. 30 tons / 12 ft x 8 ft x 9 ft (H) app. A similar 8 MW, 12 pole machine will likely have 20% bigger size and would weigh probably 30% more. Muthu www.edison.co.in

NTC resistors OEM links (pdf alert) https://www.eaton.com/content/dam/eaton/products/electronic-components/resources/technical/eaton-ntc-thermistors-app-note-elx1247-en.pdf https://cdn.soselectronic.com/productdata/71/15/e533b543/s-237-5-b57237-s509-m.pdf Muthu www.edison.co.in

5100 RPM (85 Hz) GT driving a 3000 RPM (50 Hz) generator via a gear box is showing high vertical vibrations during startup (after a year-long shutdown) in GT front bearing (NDE) as below. GT rear bearing (DE) also showing similar high vibrations. Both GT and generator white metal bearings are...

Thanks jghrist. Got it. Would it work if another phase is taken as 0 deg? (Wish I could give more LPS). Muthu www.edison.co.in

Thanks jghrist . Your calculation tracks what I measured at neutral. If I may ask, how did you arrive at 0, 119, 119 angles ? waross - Input voltages are pretty much equal. It's regulation that is the issue. I had the utility guy measure the voltages at their transformer end, which is about 600...

Neutral current at low load was 2 Amps jghrist - The angles between the phasors A1, A2 and A3? How would you plug in these angles in your Excel sheet? Muthu www.edison.co.in

How many leads are on the motor terminals, 6 or 9? Post a photo of the motor terminal box. Muthu www.edison.co.in