CSA circuit breaker standards

[PRW]

I am building some equipment for use in Canada and it must comply with CSA. The motor/reducer being used is 42VAC/3PH and will be controlled by a VFD. The data plate on the motor shows 4.9 Amps with a SF of 1.0.

I don't have a copy of their code, but will purchase one as a last resort as we seldom do work for Canada. Hopefully someone here on the forum has one and can help.

Does their code state what size the circuit breaker should be?

Thanks,

Paul

 

[waross]

I just spent about an hour searching the CEC and the answer appears to be NO, there is no specific code for VFDs in a non hazardous location.
I would treat the VFD as a piece of electrical equipment with no special starting requirements and protect it accordingly.
The CEC generally accepts a 15 amp breaker as adequate protection for any normal load that would otherwise require a smaller rating.
Is anyone else able to add to this?
I believe that the Canadian Electrical Code is available for purchase and download online. Found under Canadian Standards Association.
For DOL starting of a three phase induction motor, a 15 amp breaker is acceptable for any motor up to 9 amps full load current.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[X49]

The minimum breaker size is 125% of the VFD nameplate input current (not the motor nameplate current), and then rounded up to the nearest size. In your case, the nearest size may be 15A if you're using a breaker, which is acceptable by Canadian code.

However, you may consider using high speed drive fuses in a smaller size for better short circuit protection for the drive. Check to see what the drive manual recommends. Its recommendations will also comply with the CEC as long as the drive is CSA/cUL rated.

 

[waross]

Hello X49. Did I miss a specific rule or are you using the generic 80% of capacity rule for continuous loads rules?
Thanks.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[controlsdude]

When I did projects for Canada, I remember that all electrical parts had to have CSA stamps on them to comply with their standsrds. But that has been years back and know that CSA-cUL is another standard that they go by. Again, CSA electrical inspection was looking at CSA parts and electrical spacing requirments.

 

[waross]

Be aware that CSA Part 1 which we have been quoting is for field installations only.
If you are sending a design to be field built this standard is applicable.
If you are building and shipping the panel then other standards apply. In your position I would consider sending my design to a control panel building shop and have them build and certify the panel. If your shop has authority to certify panels you you can probably get the certification accepted in Canada.
You may have to apply for a local inspection and approval. The local approvals I have done were cheap, easy and painless.
In most instances the approval from another jurisdiction was accepted. The one exception was the flexible supply cable to a large dough mixing machine. The inspector passed the machine but required us to replace the flexible cable.
There was a reasonable fee for the inspector to attend the site and approve one machine. A further charge of about 20% for each additional machine to inspect at the same time.
That was some time ago. Does anyone have more recent experience??

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[X49]

Bill,

As far as I can tell, there is no specific rule for VFD's so I used the generic 80% rule. This is backed up by the recommendations of Allen Bradley for the minimum fuse sizes for their drives, which are CSA labelled.

For instance, for a drive with an input rating of 93A, they recommend a minimum fuse size of 125A and a maximum non-time delay fuse size of 375A. The maximum size is apparently chosen to comply with CEC 28-200, but I see no reason to size a fuse this large for a drive. Some suppliers I have dealt with will recommend sizing fuses in the 150%-200% range to reduce the risk of nuisance tripping, however.

In my opinion, there really should be a section in the CEC specific to drives. It seems odd to treat them as regular motor branch circuits.

 

[X49]

If you need to get the panel certified as CSA-compliant, there are many labs that can do this for you. CSA and cUL are the most common, but there are a couple of dozen other labs that can put their own CSA-equivalent certification on the equipment. You'll need to check with the local inspection authority for a list of which are accepted.

 

[PRW]

There seems to be some confusion, which is my fault, for which I apologize. I am not building any controls, just a motor driven electroplating barrel.

Our partner in this project is providing the VFDs and might be driving multiple barrels with one VFD. My guess is that they will put a circuit breaker between the VFD and each of the barrel stations. If the gearmotor is rated at 4.9 Amps, what size breaker will they need?

 

[waross]

15 Amps for anything up to 9 Amps nameplate current, three phase.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[X49]

In addition to the 15A breakers, you will also require separate overload protection for each of the motors.

 

[dbaird]

Rockwell has a publication on North American Standards you might want to review to see if it answers your concerns:

http://search.rockwellautomation.co...m=20&requiredfields=xlanguage:MU|xlanguage:EN

David Baird
Sr Controls Designer
EET degree.

http://www.afctool.com

 

[automatic2]

The CEC accepts O/L rated VFDs as full filling the requirement for overloads. They do not speak to VFDs as having any influence on overcurrent, and one handles it as either a motor, transformer, or demand load. Motors being 250% FLA max for breakers. VFDs are not considered acceptable for disconnects should they be required.

 

[X49]

automatic,

VFD's are normally acceptable for overload protection. However, when running multiple motors from a single VFD, separate protection is always required since the VFD O/L trip must be set higher than any of the individual motor current ratings.

 

[automatic2]

absolutely. In that case it's multiple motors on a single O/C, each requiring O/L.