Re: DC Brushless Blower Motor

[peter merguerian]

Brian,

 

I assume 24 Vdc derived from a secondary isolated circuit. Like a transformer
in a switch mode power supply, the motor can be evaluated to the end-product
standard, it does not have to be an approved component. However as part of
their investigation, the NRTL or other certification body may be asking for
the blower construction details such as winding wire size, insulation class,
polymeric materials used, etc. Depending on the NRTL or certification body,
some or all of these parts may be tied down as critical components. During the
NRTL or certification body follow-ups, these critical components become
subject to inspection. Depending on the inspector visiting the factory, he/she
may be asking to verify the parts meet the specs in the critical component
list. This can be easily resolved by obtaining a CoC for every shipment from
the blower manufacturer. The CoC can show drawings of the blower construction
(magnet wire manufacturer, type and class, polymeric material manufacturer and
grade designation, etc.

 

To make the story short, no the blower does not have to be approved. It can be
evaluated as part of the end-product standard.

 

Best Regards,

 

Peter

--- On Wed, 6/25/08, Kunde, Brian  wrote:


From: Kunde, Brian 
Subject: DC Brushless Blower Motor
To: emc-p...@ieee.org
Date: Wednesday, June 25, 2008, 5:58 AM



Our engineering group wants to use a small cross flow blower that has a
brushless DC motor rated 24Vdc at only 1 amp. The blower assembly and motor
does not have any safety agency approvals though it is built by a reputable
motor company.   Our company has a general rule that all motor devices must
have UL, CSA and either TUV or VDE agency approval.  Unfortunately, this
blower assembly is not common and engineering cannot locate a compatible
blower that has agency approvals.

 

Being that the blower motor is only 24Vdc at 1 amp and it is brushless, 
I
assume the risk of fire is low.  We could perform the locked rotor test and
limit the input current.  What other safety tests could be performed to
adequately evaluate the use of this blower?  Are there any safety standards
specific to dc brushless motors?  Would an NRTL require this kind of motor to
have agency approvals?

Thanks in advance,

The Other Brian

 

 

 

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Re: DC Brushless Blower Motor

[Ted Eckert]

The risk of fire for the blower may be mitigated by the selection of the power
source.  If you use an LPS to provide power, the risk of fire should be fairly
low.  By limiting the power source, you can ensure that there won¢t be enough
energy supplied to the blower to cause a safety issue.  

 

NRTLs may still require some type of approval for the blower.  My experience
with UL is that they are going to either ask for a UL recognized fan or they
will require you to test it in your end application.  The latter option can be
a bit difficult on a brushless motor.  UL¢s test procedures for fans and
motors are largely based on AC induction motors.  A brushless motor has a
simple electronic commutation circuit.  If it is a single speed motor, you may
be able to do a locked rotor test.  Many of these brushless motors have locked
rotor detection built in.  They will shut off current to the windings when the
rotor is locked.  I had a project where I had an electronically commutated DC
motor that did not have the required internal UL thermal protection on the
windings.  This was for an air conditioner, so UL brought in their UL 507 fan
group to look at the fan.  UL required me to test it in my end application by
overriding the locked rotor protection.  That couldn¢t be done without
disabling the motor completely.  UL and I eventually came to the agreement to
run a test by loading the motor as much as possible before the locked rotor
circuit kicked in.  Even then, the windings were quite cool relative to the
safety limit.

 

Since this is a 24 VDC blower, you can probably avoid testing by having
acceptable external protection.  Talk to your NRTLs, but they are likely to
accept an unapproved part if you can show that you have protected the power to
the point where there is not enough energy to cause a problem.  Many of the
people in UL¢s fan and motor groups come from a mechanical background and not
an electrical background.  Try to keep the project with an electrical group. 
Once the motor groups get dragged in, requirements that are not applicable to
this motor type may be applied.

 

Ted Eckert

The opinions expressed are my own and are not necessarily those of my employer.



--- On Wed, 6/25/08, Kunde, Brian  wrote:


From: Kunde, Brian 
Subject: DC Brushless Blower Motor
To: emc-p...@ieee.org
Date: Wednesday, June 25, 2008, 7:58 AM



Our engineering group wants to use a small cross flow blower that has a
brushless DC motor rated 24Vdc at only 1 amp. The blower assembly and motor
does not have any safety agency approvals though it is built by a reputable
motor company.   Our company has a general rule that all motor devices must
have UL, CSA and either TUV or VDE agency approval.  Unfortunately, this
blower assembly is not common and engineering cannot locate a compatible
blower that has agency approvals.

 

Being that the blower motor is only 24Vdc at 1 amp and it is brushless, 
I
assume the risk of fire is low.  We could perform the locked rotor test and
limit the input current.  What other safety tests could be performed to
adequately evaluate the use of this blower?  Are there any safety standards
specific to dc brushless motors?  Would an NRTL require this kind of motor to
have agency approvals?

Thanks in advance,

The Other Brian

 

 

 

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RE: EMC in the news: RFID & Medical

[Conway, Patrick R (Houston)]

...and if you put four of them in a circle, you can pop corn.  :)
 
 
 
Best Regards, 

Patrick. 
p.con...@hp.com 

 



From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Rudd, Adam
Sent: Wednesday, June 25, 2008 7:19 AM
To: emc-p...@ieee.org
Subject: EMC in the news: RFID & Medical



“The latest research, conducted at Vrije University in Amsterdam, tested the
effect of holding both "passive" and powered RFIDs close to 41 medical
devices, including ventilators, syringe pumps, dialysis machines and
pacemakers.

A total of 123 tests, three on each machine, were carried out, and 34 produced
an "incident" in which the RFID appeared to have an effect - 24 of which were
deemed either "significant" or "hazardous".

In some tests, RFIDs either switched off or changed the settings on mechanical
ventilators, completely stopped the working of syringe pumps, caused external
pacemakers to malfunction, and halted dialysis machines.

The device did not have to be held right up to the machine to make this happen
- some "hazardous" incidents happened when the RFID was more than 10 inches
away.”

--http://news.bbc.co.uk/2/hi/health/7471008.stm
 

Best Regards,

Adam Rudd

Electrical Engineer (EMC)

NCR Corporation, RHSS

Duluth, GA

(770) 495-2825

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RE: EMC in the news: RFID & Medical

[Umbdenstock, Don]

125 kHz and 868 MHz.  Interestingly, one would think filtering at the higher
frequencies would be easier to implement, but indications are that the higher
frequency had more hits.

It doesn’t indicate the degree of compliance with the medical devices
immunity requirements.

Don 
561 912  6440 



From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Andrew McCallum
Sent: Wednesday, June 25, 2008 8:39 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: EMC in the news: RFID & Medical

 

Be interesting to see exactly what they tested. 

Was the medical equipment built to the current Medical Equipment Directive or
not.

What frequencies did the RFID equipment work on.

Was it the reader or the tag that was 10cm away from the affected equipment.

Need to see the full report

 

Regards

 

Andy

 

 




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DC Brushless Blower Motor

[Kunde, Brian]

Our engineering group wants to use a small cross flow blower that has a
brushless DC motor rated 24Vdc at only 1 amp. The blower assembly and motor
does not have any safety agency approvals though it is built by a reputable
motor company.   Our company has a general rule that all motor devices must
have UL, CSA and either TUV or VDE agency approval.  Unfortunately, this
blower assembly is not common and engineering cannot locate a compatible
blower that has agency approvals.

 

Being that the blower motor is only 24Vdc at 1 amp and it is brushless, I
assume the risk of fire is low.  We could perform the locked rotor test and
limit the input current.  What other safety tests could be performed to
adequately evaluate the use of this blower?  Are there any safety standards
specific to dc brushless motors?  Would an NRTL require this kind of motor to
have agency approvals?

Thanks in advance,

The Other Brian

 

 

 

_ 

LECO Corporation Notice: This communication may contain confidential
information intended for the named recipient(s) only. If you received this by
mistake, please destroy it and notify us of the error. Thank you. 
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EMC in the news: RFID & Medical

[Andrew McCallum]

Be interesting to see exactly what they tested. 
Was the medical equipment built to the current Medical Equipment Directive or
not.
What frequencies did the RFID equipment work on.
Was it the reader or the tag that was 10cm away from the affected equipment.
Need to see the full report
 
Regards
 
Andy
 





Confidentiality: This e-mail and its attachments are intended for the
addressees only (or people authorised to receive them on their behalf) and may
be confidential or privileged. If they have come to you in error you must take
no action based on them, nor must you copy or show them to anyone; please
delete them from your system and reply to this e mail highlighting the error.

Security: Please note that this e-mail has been created in the knowledge that
internet e-mail is not 100% secure. Anyone who communicates with us by e-mail
is taken to accept this.

Viruses: We have taken steps to ensure that this e-mail and attachments are
virus free, but we advise that in keeping with good computing practice you
should ensure that they are actually virus free. 




DeltaRail Group Limited registered office Hudson House, 2 Hudson Way, Pride
Park, Derby, DE24 8HS. Registered in England and Wales, number 5839985. Please
refer to www.deltarail.com 
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EMC in the news: RFID & Medical

[Rudd, Adam]

“The latest research, conducted at Vrije University in Amsterdam, tested the
effect of holding both "passive" and powered RFIDs close to 41 medical
devices, including ventilators, syringe pumps, dialysis machines and
pacemakers.

A total of 123 tests, three on each machine, were carried out, and 34 produced
an "incident" in which the RFID appeared to have an effect - 24 of which were
deemed either "significant" or "hazardous".

In some tests, RFIDs either switched off or changed the settings on mechanical
ventilators, completely stopped the working of syringe pumps, caused external
pacemakers to malfunction, and halted dialysis machines.

The device did not have to be held right up to the machine to make this happen
- some "hazardous" incidents happened when the RFID was more than 10 inches
away.”

--http://news.bbc.co.uk/2/hi/health/7471008.stm
 

Best Regards,

Adam Rudd

Electrical Engineer (EMC)

NCR Corporation, RHSS

Duluth, GA

(770) 495-2825

-  This
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