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BOAT YACHT HVAC - Unbalanced Phases and Harmonics - Single-phase motor coggs only when feed from generators.
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<blockquote data-quote="Miami Boat Electrician" data-source="post: 534531" data-attributes="member: 35603"><p>I will try that and report back. Thank you.</p><p></p><p>Those two motors works well when connected to the public network, and also work well when only one generator is operating ( any generator); by just rotating the manual commuting drum switches of each independent panel. </p><p></p><p>Only when the 2nd generators enters in operation, the intermittent sporadic cogging happens, “both motors cogg simultaneously” as they are in same panel and same branch circuit breaker. I have also commuted this specific panel to one or another generator, with same failure. </p><p></p><p>Without couple of “recording testers” it is difficult to catch the precise moment when, The voltage variation from a “momentary unbalance” caused by a non-identified-yet “momentary load” ( or starting motor) is also feed by the generator.</p><p></p><p>Both generators have their own independent neutral, connected to their own frame. But frames are interconnected by the whole yacht “earth” network. </p><p><strong>Would it be irrelevant if the return line of the motor is connected to a different neutral bar ?</strong></p><p></p><p>It has to be simpler than all the following complex theory, as it should be common issue in real life for years and years…. Here is where your experience becomes PURE GOLD <img class="smilie smilie--emoji" loading="lazy" alt="😀" title="😀" src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f600.png" />:</p><p></p><p>THEORY</p><p>Cogged motor means “a” or “b”</p><p>a. 5th or 7th harmonic braking, </p><p><strong>Any idea of How to select, and obtain a harmonics filter? </strong></p><p> ( the harmonics are produced within the airgap between Rotor & Stator from both: 3-Ph Generator and 1-ph motor; more likely in the small 1-phase capacitor-Start-motor; usually adding a lineal load as a lightbulb increases the active current, creating a different ratio with the reactive current. </p><p></p><p>or</p><p></p><p>b. Low torque resulting from reduction of the ratio {Volt/Hz}:</p><p>- A 3hz difference will lower torque by only 5% , </p><p>- But a 15% Voltage drop in case of unbalanced phases could reduce torque by 15%, and cogg the motor. </p><p></p><p>Probably another phase is been loaded/unloaded causing a generator 3-phases unbalance, and consequently a low voltage , cogging the air conditioner’s fan motor.</p></blockquote><p></p>
[QUOTE="Miami Boat Electrician, post: 534531, member: 35603"] I will try that and report back. Thank you. Those two motors works well when connected to the public network, and also work well when only one generator is operating ( any generator); by just rotating the manual commuting drum switches of each independent panel. Only when the 2nd generators enters in operation, the intermittent sporadic cogging happens, “both motors cogg simultaneously” as they are in same panel and same branch circuit breaker. I have also commuted this specific panel to one or another generator, with same failure. Without couple of “recording testers” it is difficult to catch the precise moment when, The voltage variation from a “momentary unbalance” caused by a non-identified-yet “momentary load” ( or starting motor) is also feed by the generator. Both generators have their own independent neutral, connected to their own frame. But frames are interconnected by the whole yacht “earth” network. [B]Would it be irrelevant if the return line of the motor is connected to a different neutral bar ?[/B] It has to be simpler than all the following complex theory, as it should be common issue in real life for years and years…. Here is where your experience becomes PURE GOLD 😀: THEORY Cogged motor means “a” or “b” a. 5th or 7th harmonic braking, [B]Any idea of How to select, and obtain a harmonics filter? [/B] ( the harmonics are produced within the airgap between Rotor & Stator from both: 3-Ph Generator and 1-ph motor; more likely in the small 1-phase capacitor-Start-motor; usually adding a lineal load as a lightbulb increases the active current, creating a different ratio with the reactive current. or b. Low torque resulting from reduction of the ratio {Volt/Hz}: - A 3hz difference will lower torque by only 5% , - But a 15% Voltage drop in case of unbalanced phases could reduce torque by 15%, and cogg the motor. Probably another phase is been loaded/unloaded causing a generator 3-phases unbalance, and consequently a low voltage , cogging the air conditioner’s fan motor. [/QUOTE]
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BOAT YACHT HVAC - Unbalanced Phases and Harmonics - Single-phase motor coggs only when feed from generators.
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