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  1. G

    How to do a proper insulation test (Megger test) on a 3-phase 400V asynchronous squirrel cage motor?

    Understood, thank you, Phil.
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    How to do a proper insulation test (Megger test) on a 3-phase 400V asynchronous squirrel cage motor?

    I want to check the insulation of the 3-phase 400VAC asynchronous squirrel cage motor. Motor's stator windings are connected in delta. I've read in some textbooks it is necessary to open motor's junction box and disconnect terminals and remove jumper bars (which are used to establish delta or...
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    Grid frequency unstable - potential problems?

    Hello again! I just wanted to give a small update since I am back on the yacht. So, the gensets overhaul didn't help - the issues still persists. CSA, you understand very well what dry dock is! Looking through handovers of my past colleagues all the way to 2014, there is no mention of this...
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    AGM batteries constantly charged. Can it damage them?

    Thank you, I do believe you are right. The best suited test for the batteries which serve as a backup batteries (meaning, they have to provide 50-100A current for 30-120 min; I will have to check the exact figure) is indeed a run-down test. That way I can see if the batteries will provide...
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    AGM batteries constantly charged. Can it damage them?

    So, I ve contacted manufacturer and got a reply: They're saying that there is no problem whatsoever if batteries are constantly connected to the charger. You just need to make sure that the charger setting is set to the adequate battery type (in this case, AGM) and that temperature sensor is...
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    AGM batteries constantly charged. Can it damage them?

    I am pretty sure all load is supplied by the charger, but I will double check it. There is also a backup charger of the same type connected to these batteries. How exactly do you perform charge equalization? I am measuring CCA with the Midtronics MDX-700HD. I am measuring CCA in a way...
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    AGM batteries constantly charged. Can it damage them?

    Thank you. Then I have to keep looking for the reason why my batteries' capacity is dropping so fast. The batteries CCA have dropped 50% in 2.5 years...
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    Grid frequency unstable - potential problems?

    S Sorry to disappoint you. I have neglected this topic despite all your help. My contract on the ship ended and I went home. We stopped troubleshooting this problem and just left it as it is. It still persists, but we will do nothing about it. That is the summary.
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    AGM batteries constantly charged. Can it damage them?

    Batteries: 6 x AGM Mastervolt 12V 225Ah (3 sets of 2 12V batteries connected in series, 24V per set; sets connected in parallel) - https://www.mastervolt.com/products/agm-12v/agm-12-225-group-8d/ Charger: Mastervolt MASS 24/75C...
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    Grid frequency unstable - potential problems?

    Hi, We are currently in the shipyard, connected to shore power because our gensets are being overhauled. Of course, frequency is now very stable at 50.02Hz.
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    Grid frequency unstable - potential problems?

    Wow, what a wealth of information! Please excuse me for not replying quickly. I am quite busy right now as we are entering dry dock tomorrow and will reply as soon as I process your info. Thank you!
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    Grid frequency unstable - potential problems?

    First of all, I can't believe you are this kind to write in so many details to try to help me. It's just amazing! I have one small observation that might be helpful: When observing Local operating panel (the panel where you can operate genset locally and see engine and alternator parameters)...
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    Grid frequency unstable - potential problems?

    What is an SOE? Let's say load sharing scheme is not tuned properly. Would this matter if only one genset is online? My humble opinion is that load sharing scheme is not important when there is just one genset online because no load is being shared, all the load is taken by one genset. Am I...
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    Grid frequency unstable - potential problems?

    @ControlsGuy25 and @CSA Thank you sooo much for your input! Since I am not on your level of expertise, I will need some time to read several times what you have written and then some time to try to understand it, so I can provide you with the best possible information. Once again, thank...
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    Grid frequency unstable - potential problems?

    What is not well tuned? What should I search for in PMS data?
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    Grid frequency unstable - potential problems?

    H&H is Heinen and Hopman, it's a company doing HVAC systems. Right now, we have one generator running - around 250kW and 25kVA, so power factor is around 0,9.
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    Grid frequency unstable - potential problems?

    Unbelievable, but we don't have a Power factor meter readily available! I just learned that now! Maybe we have it somewhere in the PMS, I will have to check... The moost comprehensive load balance sheet I found can be seen on the link below...
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    Grid frequency unstable - potential problems?

    Shore connection is just an option to connect to the shore grid once we are alongside. We rarely use this, so this is not our problem. The frequency instability is constant, it only changes as I described in my 1st post.
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    Grid frequency unstable - potential problems?

    I am sorry, but could you please explain what is an "sld". I will assume you mean a drawing of our distribution system. It is attached. Also, what does it mean to "develop on grid system"? If you mean, to describe our on-grid system, you can check the attached drawing. If anything is unclear...
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    Grid frequency unstable - potential problems?

    I work onboard a yacht where we have 3 pieces of 765kVA diesel gensets composed of the engine MTU 12V2000 M51A and the alternator Stamford HCM634J2. The gensets are producing 3 phase 400VAC/50Hz. First of all, I am not sure if there is even a problem with the gensets so here goes my first...
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