Those are true statements, but I would say that the cooling fan at the opposite end of the output shaft makes the most noise. Depending on the motor there are many different designs. The magnetic flux between the armature and the field coils oscillate as it cycles, such as a speaker operates, the housing of the motor accentuates this oscillation. Airflow around the spinning parts also. This also can apply to a solid magnet field of a DC motor.
Sometimes inferior manufacturing can also contribute, such as; inferior bearings, bad balancing of the armature, poor bonding of the laminations, etc Any time there is an oscillation in any sound conducting environment or medium, there is always noise. Hi Guys The motor was purchased new a decade ago and run by VFD since day one for a total of only about hrs. I have disassembled the motor and found that the sealed bearings felt good.
No catching or roughness and a little drag, not dry endless spinning. It's also possible that during boiler re-fill, instead of removing previous trapped air, we are left with new, worse air trapped in the system. Just what sort of noise air makes in a hot water heating system will depend on the orifices through which it is being forced. I speculate that that can create a wide range of sounds, not all of which would be polite to describe.
There may be two other sounds from your system that bear thought 2. Vibration noises, for example transmission of normal vibration from an oil burner motor through oil piping or other metal parts into the building structure or piping. Creaks and clanks can occur where pipes move through walls and floors as they expand and contract during heating system operation. A "sneezing noise" could be a valve or vent opening or operating normally All of these sounds can be fixed.
I'm not sure why you drained the system in the first place. Saying "there's not much air in the pipes" is like saying "our cat is only a little-bit pregnant". That's not the best analogy since even if there were only a little air that was observed, there could have been a greater amount of air that the plumber didn't find and thus didn't observe.
In any case, draining and presumably re-filling the boiler with water is not a repair for noises. And for hot water heat there are some small disadvantages in doing so increasing the level of minerals in the system, for example. That suggests that maybe your plumber was not an expert on hydronic heating and air purging. She should have. I have been eagerly reading your contents regarding noises in a heating system. If the answer is within, I have not found it yet.
Hopefully you can help. We have a gas fired boiler with baseboard heaters. Relatively small house, it's a 3 bedroom cape built around , and the boiler was replaced just before we moved in It's a Burnham hydronics series 2, I started by having a plumber drain the system, there are three zones.
He flushed each one as I looked on trying to learn how to do it. When he was done, he said there wasn't much air in the pipes at all. And of course, it did not make a difference with the noises we experience. This relatively low-volume, low-frequency beating of higher frequency components may be objectionable because it is intermittent. Being a function of slip, it is more noticeable under load, with the frequency varying directly with slip.
Causes may include an open rotor bar or end ring, but slip noise is usually associated with a defect in the uniformity of the squirrel-cage rotor, the remedy for which is a new rotor. A common suggestion is to skew the rotor, at least one rotor or stator slot whichever has fewer slots. Anything less will not reduce magnetic noise appreciably, and larger skews usually degrade motor performance. Unequal air gap.
An unequal air gap causes unbalanced magnetic pull with stronger magnetic forces in the direction of minimum air gap see Figure 2. This can deform the stator, rotor and frame while generating electromagnetic noise.
Running the motor at reduced voltage is a simple diagnostic tool. For example, if the motor is noisy at full voltage but sounds fine at half of rated voltage, focus on the air gap and such issues as mis-machined housing or an eccentric rotor. Manufacturing variations affect the magnetic noise of slower speed motors more than they do two-pole motors. For example, the air gap for a six-pole motor with a inch mm OD stator could be 0.
The sources of mechanical noise in a motor include a loose stator core; worn, damaged or poorly lubricated bearings; and rubbing of internal components.
Additionally, any structural part of the motor that is excited at its natural frequency can become the source of airborne noise. Loose stator core. A stator core that is loose in the frame will cause a buzzing noise. If tapping deforms the frame-to-core fit, the noise level will change or may even cease. Strictly speaking, the source of this noise is magnetic, so the noise will also cease when the power is removed.
Bearings are a frequent source of mechanical noise in motors. Excessively noisy rolling element bearings, for example, may be traceable to nonuniform balls or rollers, rattling ball or roller retainers, poor surface finish, or eccentricity. Besides impact noise, these conditions can result in resonance excitation of bearing housings, air deflectors baffles and other parts that radiate noise efficiently.
Noise in the to Hz frequency range is characteristic of rolling element bearings and may be due to the passage of the balls or rollers. Usually, this noise is low amplitude and not physically detrimental unless it excites the natural frequencies of other motor parts and causes damaging vibration. Typical methods are;. The methods 1 and 2 can work. However, the combination of 1 and 2 is often the most effective way to reduce the electrical noise.
In measuring a mechanical noise, the noise level loudness is physically measured by a noise meter.
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