400V 50HZ operate on 480V 60 HZ

[winnie]

Moderators and others forgive

My continue questions

Back to quote

1500rpm fan and 1800rpm fan

at 1800rpm

absorb same hp almost

It little difference to the motor

6/5x6/5x6/5 times rated hp require still apply.

Motor overload may

I have a fan which uses 1Hp of mechanical power when spinning at 1800 RPM on a 4 pole 60 Hz motor.

Are you saying that if I take this same fan, place it on a 4 pole 50 Hz motor (which normally operates at 1500 RPM) and then operate the motor at 60Hz so the fan spins at 1800 RPM, the fan will suddenly require (6/5)^3 = 1.73 Hp?

Or are you saying that the motor will somehow become far less efficient?

Also, it is clear that English is not your first language. Are you using some sort of machine translation tool that might be messing up our understanding of each other?

-Jon

 

[Jraef]

The insulation system presents a limit, but is usually not a problem for motors below 600V. Pretty much all the same magnet wire is used for low voltage 'mush wound' motors.

The motor bearings will be operated at higher speed and have a shorter life in terms of operating hours.

For large motors you end up bumping into the maximum rotational speed of the rotor.

In the US, NEMA design motors are often expected to be capable of operating at higher then 60 Hz; see table 30-1 on page 10 of https://www.nema.org/docs/default-s.../mg-1-part-30-watermark.pdf?sfvrsn=793de734_1

The larger the motor is the less you can push it above 60Hz. A 1 HP 2 pole motor (nominal 3600 RPM) is expected to be safely operable at 120 Hz (7200 RPM) But a 30Hp 2 pole motor is expected to safely operate up to 90Hz, and a 60Hp 2 pole machine is limited to 60Hz.

-Jon

In days past I would tend to agree on the motor insulation risk, but last time I went to an EASA convention, NONE of the magnet wire manufacturers were offering anything less than 1600V insulation now. It no longer makes sense for them to have 3 or 4 different production lines just to save a few pennies per thousand feet by having lower insulation ratings.

 

[Deltaforce]

I have a fan which uses 1Hp of mechanical power when spinning at 1800 RPM on a 4 pole 60 Hz motor.

Are you saying that if I take this same fan, place it on a 4 pole 50 Hz motor (which normally operates at 1500 RPM) and then operate the motor at 60Hz so the fan spins at 1800 RPM, the fan will suddenly require (6/5)^3 = 1.73 Hp?

Or are you saying that the motor will somehow become far less efficient?

Also, it is clear that English is not your first language. Are you using some sort of machine translation tool that might be messing up our understanding of each other?

-Jon

1500rpm fan and 1800rpm fan

Hp require of 1800 rpm fan 6/5*6/5*6/5 times that 1500 rpm fan

ie 1800rpm fan hp require more than 1500rpm fan

50hz 400v motor need supply hp to 1800rpm fan 6/5*6/5*6/5 times that 1500rpm fanl

NB- Thanks forebearance my language.

 

[winnie]

1500rpm fan and 1800rpm fan

Hp require of 1800 rpm fan 6/5*6/5*6/5 times that 1500 rpm fan

ie 1800rpm fan hp require more than 1500rpm fan

50hz 400v motor need supply hp to 1800rpm fan 6/5*6/5*6/5 times that 1500rpm fanl

NB- Thanks forebearance my language.

This is not correct. If you are comparing two _different_ fans, then there is no relation between fan speed and power requirement. The affinity law you describe is for a particular fan spinning at different speeds.

A 1800 RPM 1 Hp fan requires 1 Hp of mechanical power input. In SI units, it requires 4 newton meters of torque at 188.5 radians per second for 746 watts.

A 1500 RPM 1 Hp fan requires 1 Hp of mechanical power input. In SI units, it requires 4.75 newton meters of torque at 157 radians per second for 746 watts. This is a _different_ fan, with different blade size or pitch or shape than the '1800 RPM 1Hp fan' described above.

If I were to take this fan, designed to run at 1500 RPM using 1 Hp of mechanical power, and spin it at 1800 RPM, I'd expect it to use (6/5)^3*746=1290W, or about 1.73 Hp. But that is _not_ the case here. Here we have fan intended for use at 1800 RPM being used at 1800 RPM.

-Jon

 

[kwired]

1500rpm fan and 1800rpm fan

Hp require of 1800 rpm fan 6/5*6/5*6/5 times that 1500 rpm fan

ie 1800rpm fan hp require more than 1500rpm fan

50hz 400v motor need supply hp to 1800rpm fan 6/5*6/5*6/5 times that 1500rpm fanl

NB- Thanks forebearance my language.

The fan was originally running at 1800 rpm.

replacement 60 hz motor not available so is replacing with a 50 Hz motor but still running at 60 Hz and at 460 instead of 400. Output shaft will be turning same speed as original motor, this will turn fan at same speed it originally ran at, that will impose same mechanical load on the motor.

It may draw slightly different current because of inefficiencies or minor details but for most part will be driving same load at same rate as was the original motor.

 

[Jraef]

1500rpm fan and 1800rpm fan

Hp require of 1800 rpm fan 6/5*6/5*6/5 times that 1500 rpm fan

ie 1800rpm fan hp require more than 1500rpm fan

50hz 400v motor need supply hp to 1800rpm fan 6/5*6/5*6/5 times that 1500rpm fanl

NB- Thanks forebearance my language.

He never had a 1500RPM fan.

It has always been and still is a fan based on 1800RPM.

You have been making assumptions and missing details that are artificially extending this discussing into irrelevant side issues that may confuse the OP and others who read this later.

Please cease.

 

[Deltaforce]

Great learning experience my

Start another thread

Regards voltage relate possible damage for motor of OP per NEMA and IEC standards

Thanks

 

[electrofelon]

Regards voltage relate possible damage for motor of OP per NEMA and IEC standards

Thanks

unlikely extremely, post #82 see.

 

[kwired]

unlikely extremely, post #82 see.

and on top of that this is a way of solving the problem when the original motor isn't available, so OP goes in knowing there could be some chance it won't last as long as the original motor. Still with some the information presented this motor likely will last a long time unless as mentioned the original was designed to run at a service factor higher than 1.0.

 

[Deltaforce]

unlikely extremely, post #82 see.

1.6kV in #82 impulse withstand voltage motor insulation

Not motor rated voltage over voltage operation

Discuss in another thread

#86 refer

 

[ActionDave]

Not discuss, not refer, not longer any. Closed thread.