Buzzing Mcb

[Lilyrose08]

Just recently installed a lighting circuit on a wylex type b 6amp Mcb and recently noticed its been buzzing I have changed it and it still buzzes all connection are tight what could it be there's dimmers on the circuit and 5 watt led lamps any ideas

 

[shocking_eg]

LED's cause MCB's to buzz, usually when there are quite a lot on the same MCB.

Iv never had any issues, something to do with the high inductive load i think... not sure if it can damage the MCB in the long run ?

 

[KAS1]

Does it buzz just before it trips or does the trip still just about holds in while it's buzzing

 

[shocking_eg]

Does it buzz just before it trips or does the trip still just about holds in while it's buzzing

dont think its been tripping ?

 

[MDJ]

not fixed to the busbar properly? it is easy to have the busbar behind the terminal and you may think it's tight but it is in fact not even connected, over load maybe? whats the total load on the breaker? faulty MCB, wylex had a recall of 6 amps 18 months ago, a few may have escaped the recalls?

 

[Stuuk1]

http://www.electriciansforums.net/e...-electrical-forum/48514-why-do-mcbs-buzz.html

 

[Lilyrose08]

It's not tripping the circuit has been tested and all results are fine

 

[shocking_eg]

not fixed to the busbar properly? it is easy to have the busbar behind the terminal and you may think it's tight but it is in fact not even connected, over load maybe? whats the total load on the breaker? faulty MCB, wylex had a recall of 6 amps 18 months ago, a few may have escaped the recalls?

i have seen it a lot.

the actual MCB buzzes, not where the connection sits on the bus bar, so no arching going on.

does it with all makes of MCB

 

[Sintra]

Could be a conflict between dimmers and LED drivers causing harmonics. Dimmer leading edge and driver trailing edge or vice versa.

 

[Marvo]

The dimmers could be the issue, they have a diac/triac and trigger cap which have a tendancy to cause harmonics which in turn can cause the MCB to buzz. Often with LED lighting on a dimmer the load is actually insufficient which can also cause weired triggering problems. Often if it is a dimmer induced buzz it will go away or be noticably reduced if it's set to full brightness.

 

[HappyHippyDad]

The dimmers could be the issue, they have a diac/triac and trigger cap which have a tendancy to cause harmonics which in turn can cause the MCB to buzz. Often with LED lighting on a dimmer the load is actually insufficient which can also cause weired triggering problems. Often if it is a dimmer induced buzz it will go away or be noticably reduced if it's set to full brightness.

I think your answer from 2011 was more in depth and explains perfectly :

The MCB is probably buzzing because it's close to its tripping threshold. Poor power factor and harmonics on a circuit load can also cause the MCB to buzz even if the current through it is less than its rated value.

The dimmer buzzing is probably either because it's cheap and poor quality or because it's running over its full load ability.

If the transformers are buzzing it's probably mechanical action between the laminations if they're wirewound. If they're electronic then it most likely 'cheap n' nasty' syndrome again or they're not designed to be dimmed or the wrong type of dimmer is being used (leading/trailing edge).

If the lamps are buzzing they're probably not compatible with the dimmer or the transformer.

All that said, the last buzzing control panel I investigated was caused by a massive wasps nest so it's always a good idea to keep your wits about you.

Read more: http://www.electriciansforums.net/e...rum/48514-why-do-mcbs-buzz.html#ixzz2IB7o5xE0

 

[Marvo]

Lol, I forgot to suggest he checks for wasps this time.

 

[GLENNSPARK]

I think your answer from 2011 was more in depth and explains perfectly :

The MCB is probably buzzing because it's close to its tripping threshold. Poor power factor and harmonics on a circuit load can also cause the MCB to buzz even if the current through it is less than its rated value.

The dimmer buzzing is probably either because it's cheap and poor quality or because it's running over its full load ability.

If the transformers are buzzing it's probably mechanical action between the laminations if they're wirewound. If they're electronic then it most likely 'cheap n' nasty' syndrome again or they're not designed to be dimmed or the wrong type of dimmer is being used (leading/trailing edge).

If the lamps are buzzing they're probably not compatible with the dimmer or the transformer.

All that said, the last buzzing control panel I investigated was caused by a massive wasps nest so it's always a good idea to keep your wits about you.

Read more: http://www.electriciansforums.net/e...rum/48514-why-do-mcbs-buzz.html#ixzz2IB7o5xE0

really bad on some LEDs...

 

[gnuuser]

Lol, I forgot to suggest he checks for wasps this time.

had the same problem with a small welder once.
and the damn wasp got me in the back of the neck.

 

[grantr37]

A lot of LED Drivers use Frequency Ramped Square wave drive signals to power the LED devices to illuminate all the LED's connected to a similar level, LED dimmers use frequency division drive to dim the fittings digitally, so that they can be controlled via a cheap single chip microcontroller set up.....its compact and cheap, easy to mass produce as well...




on many designs this high frequency pulse train ends up going to ground back via circuitry connected to the "neutral" tap on the miniature transformer, or via a small isolation circuit to the mains Neutral...


If there are a lot of these units connected and the Electronic noise from the driver circuit is taking a return path via the internal transformer, this can lead to high levels of Electrical distortion.....which can in turn be increased by the windings in transformers and inductors in the circuit...
Electrical noise (harmonics) due to transformer stress can be caused by physical vibration in the windings, with overloading leading to an imbalance in magnetic permeability which causes variation in magnetic field flux density, affecting the saturation of the coil windings and the level of magnetic field intensity in and around the magnetic medium(the plates) and the air gap dielectric, this can cause vibration of the transformer core and windings.....in addition overcurrent can create vibration due to thermal expansion/contraction causing transformer windings to oscillate/vibrate leading to "winding lash" where the physical vibration moves the windings to such an extent that extra Electrical noise is developed/induced at the Transformer...this noise, as well as the rapid variations in load used by the Transformer can lead to vibration in supply interconnects and breakers...


As mentioned by Marvo, when the control signal pulse train reaches a certain frequency/speed (the Digital LED dimmer gets set close to or at full brightness) this problem tends to decrease, this is because the rise and fall time and duration of the drive signal pulse is high enough to lead to saturation in the circuit (reaching resonance point) and the ripple caused by the drive signal cancels out...