The small questions thread

Forums › Off topic › The small questions thread

1 | ... | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | ... | 69

6395 posts

Uber Geek

Subscriber

#3283798 19-Sep-2024 09:00

Has the fan stopped completely? I have a Robinhood that runs for about 15 mins before stopping then it starts again at random intervals.

SomeoneSomewhere

1784 posts

Uber Geek

Lifetime subscriber

#3283983 19-Sep-2024 11:20

If the fan cannot be spun by hand or it feels quite stiff, then you have a mechanical problem: jammed, bad bearings, stuff stuck in the impeller etc.

If it can be spun freely, it is probably mechanically OK. Note BLDC fans may have some 'cogging' like computer fans where it wants to snap to the next position due to permanent magnets - this is fine.

Some types of AC motor need a run capacitor; this is usually a cylindrical or rectangular object around a cubic inch or two. You can measure it with a meter but they're cheap enough to consider replacing outright. Beware that capacitors can store a dangerous charge after being disconnected from a circuit! Measure the voltage with a DC voltmeter to check it's discharged. Shorting is not really recommended.

Live testing is not something non-qualified people should be doing, but with the power off you can check that the switches all operate and use an ohmmeter to check the contacts close. You can also check the winding resistance (should be single or double-digit ohms in a fan; no open circuits) and that, if visible, the windings are visibly OK without burning or discolouration.

Has the fan stopped completely? I have a Robinhood that runs for about 15 mins before stopping then it starts again at random intervals.

That's almost certainly a thermal protector tripping then resetting, meaning the motor is overloaded. Causes could be:

Wrong impeller for the motor is providing too much load - pretty unlikely.
Too low external air resistance causes the fan to move too much air, which causes excess torque in a centrifugal fan - possible, but not that likely in a rangehood? Unless you're operating with no duct and no filters.
Running a 50Hz fan on 60Hz supply - highly unlikely.
Run capacitor failing. Provides enough reactance to give the motor a direction of rotation but not fully contribute to keeping the motor spinning. This is quite likely.
Failing bearings - quite possible.

johno1234

2735 posts

Uber Geek

#3283995 19-Sep-2024 11:46

SomeoneSomewhere:

If the fan cannot be spun by hand or it feels quite stiff, then you have a mechanical problem: jammed, bad bearings, stuff stuck in the impeller etc.

If it can be spun freely, it is probably mechanically OK. Note BLDC fans may have some 'cogging' like computer fans where it wants to snap to the next position due to permanent magnets - this is fine.

Some types of AC motor need a run capacitor; this is usually a cylindrical or rectangular object around a cubic inch or two. You can measure it with a meter but they're cheap enough to consider replacing outright.

Live testing is not something non-qualified people should be doing, but with the power off you can check that the switches all operate and use an ohmmeter to check the contacts close. You can also check the winding resistance (should be single or double-digit ohms in a fan; no open circuits) and that, if visible, the windings are visibly OK without burning or discolouration.

Has the fan stopped completely? I have a Robinhood that runs for about 15 mins before stopping then it starts again at random intervals.

That's almost certainly a thermal protector tripping then resetting, meaning the motor is overloaded. Causes could be:

Wrong impeller for the motor is providing too much load - pretty unlikely.
Too low external air resistance causes the fan to move too much air, which causes excess torque in a centrifugal fan - possible, but not that likely in a rangehood? Unless you're operating with no duct and no filters.
Running a 50Hz fan on 60Hz supply - highly unlikely.
Run capacitor failing. Provides enough reactance to give the motor a direction of rotation but not fully contribute to keeping the motor spinning. This is quite likely.
Failing bearings - quite possible.

Be wary of motor start capacitors even after disconnecting from power - especially as found in appliances such as dryers. They can hold a significant mains voltage charge after the power has been removed. Check the voltage across the terminals carefully before touching it.

SomeoneSomewhere

1784 posts

Uber Geek

Lifetime subscriber

#3283996 19-Sep-2024 11:49

Good point; have edited to add a warning.

MadEngineer

4244 posts

Uber Geek

Trusted

#3286248 25-Sep-2024 15:15

Those of you that don’t indicate when exiting a driveway or car park similar, what’s your reason for not doing so?

You're not on Atlantis anymore, Duncan Idaho.

msukiwi

2412 posts

Uber Geek

Lifetime subscriber

#3286263 25-Sep-2024 15:24

MadEngineer: Those of you that don’t indicate, what’s your reason for not doing so?

FTFY!

SomeoneSomewhere

1784 posts

Uber Geek

Lifetime subscriber

#3286440 25-Sep-2024 23:45

msukiwi:

MadEngineer: Those of you that don’t indicate, what’s your reason for not doing so?

FTFY!

The obvious answer here is to indicate frequently and at random.

While the Land Transport Rule has various requirements for when you must indicate, there are no requirements to not indicate. Therefore, I feel the safest and most legal option is simply to always indicate in both directions simultaneously.

Behodar

10418 posts

Uber Geek

Trusted

Lifetime subscriber

#3286471 26-Sep-2024 07:59

There's even a special button for indicating in both directions!

msukiwi

2412 posts

Uber Geek

Lifetime subscriber

#3286474 26-Sep-2024 08:09

Behodar:There's even a special button for indicating in both directions!

Amazing how often I see it used on vehicles going past here etc!

johno1234

2735 posts

Uber Geek

#3286485 26-Sep-2024 08:39

Behodar:

There's even a special button for indicating in both directions!

That's for when you are turning left but identify as turning right.

Bung

6395 posts

Uber Geek

Subscriber

#3286499 26-Sep-2024 09:15

msukiwi:

Behodar:There's even a special button for indicating in both directions!

Amazing how often I see it used on vehicles going past here etc!

It's a coded signal to the Chinese Consulate from those working for the Central Committee 😎

richms

28049 posts

Uber Geek

Trusted

Lifetime subscriber

#3286545 26-Sep-2024 11:48

Behodar:

There's even a special button for indicating in both directions!

I thought that was the park my car anywhere button?

Richard rich.ms

MadEngineer

4244 posts

Uber Geek

Trusted

#3287211 27-Sep-2024 21:55

Anyone using time management software?

I'm coming from the angle of not trying to deal with lazy staff rather there are days I get to the end of and in reflection it can blow my mind on how much stuff I get through. Actually that's mostly the norm. My work flow comes in via calls, emails, an online portal and specific repeated tasks. Would love something that tracks how much time I'm spending on the phone as well as various software, this should be simple as the "phone" is actually software based, so long as it can track multi-tasking including being on an active call whilst working on software.

There are some obvious KPI's e.g. all emails in my inboxes are read or the time an email arrives in my inbox through to the time I open and delete or file it.

I'd then take that data and consider it against the likes of:

Pareto principle - Wikipedia

Kaizen - Wikipedia

I'm not under any pressure to perform, rather it's purely for self-improvement.

You're not on Atlantis anymore, Duncan Idaho.