do you need overload protection with a DOL

[--Tom--]

Hi hoping someone in the know can help.
Bought a dust extractor on ebay and it has come with the motor wired but no switching.

My thought was to add a DOL to switch it on and off. The cheaper ones say they don't come with overload protection - is this something that i need?

Motor is 0.55kw, 3.5 amp 240v

All help appreciated!

 

[Spectric]

Motors are something that can cause an overload condition where there is a large increase in current that is not great enough to take out the fuse or protective device, they are often thermal devices and can be either auto reset or on larger units manual reset. For peace of mind it is nice to know you have the protection but on such a small motor that is only in operation when you are in attendance it is debatable.

 

[--Tom--]

Thanks Spectric fully see that there are cases where you'd want one - but didn't have the knowledge to know how essential it was / risky it would be to not have one!
Being a dust extractor i'm assuming that after start up load it'll be fairly constant in it's demand (assuming no blockages)

 

[Sideways]

I owned a small record / elekra beckum extractor once that had nothing but a rocker switch fitted into the terminal box of the motor.
So don't sweat it on a small machine.

For a permanently fitted extractor, Remember that it's basically a fan. It's at risk of long term small overloads from a clogged filter or poorly designed duct work, not short term high overloads like a saw or planer might suffer taking a series of over aggressive cuts.
A VFD configured for fan duty will allow protection to be configured allowing (say) 10% continual overload, but immediate cut-off as soon as 10% is exceeded.

 

[--Tom--]

cheers, ordered a DOL, assume it’s not overly difficult to add overload protection down the line.
It’s a pedestal stand extractor just for my linisher so will be a short run of ducting

 

[--Tom--]

Hoping for a bit more help if possible

DOL arrived today, box all sealed up.

inside though I can’t find three of the terminals - they’re on the diagram but not on the actual contactor

diagram

95, 96 and 98 are not to be found though

one side with 2,4,6 and 14

Otherwise with 1,3,5, a1 & a2 with 13 under rubber cover

N and earth on the side

Wiring diagram leaves me stuck with leads w and z not having 95 and 96 to connect to.

Any thoughts on what’s needed to wire this in?

 

[guineafowl21]

A quick call to the manufacturer might be wise.

Otherwise, I would guess that the instructions cover several models, and your one is missing the options set out in the lower part of the last pic. Those missing terminals are presumably internally connected.

In that case, connect as per the text in the upper part of the last photo.

 

[--Tom--]

Thanks, yeah it doesn’t have the OL, but I can’t see how to set up the control circuit.
may need to call a spark, but thought I’d ask here as people are pretty knowledgeable and helpful!

 

[porker]

Are you sure you need to get at those points? I don't think so. I think they are already connected. To me it looks like you only need to connect up the dashed connections and put a wire link for the coil (assuming it is a mains coil). So just supply, motor, "connect link" and coil link.

 

[porker]

It looks to me like the only reason you have to add the "connect cable" is because the same switch could easily be configured to switch 3 phases.

 

[Spectric]

Hi

That is a bit overkill for a 550 watt motor, but your W & Z wires go to the start / stop buttons. In simple terms, you push the start button which energises the coil, this pulls in the contactor which then provides power to the coil to hold the contactor in. The stop button is in series with the coil, so if pushed breaks the coil supply and the contactor drops out. In your case Z is live, will go to the stop button, out to the start button and then the coil, the other side being neutral.

 

[Spectric]

Got a picture of the cover?

 

[--Tom--]

Hi

here’s the front and the spec on the side

 

[--Tom--]

Hi

That is a bit overkill for a 550 watt motor, but your W & Z wires go to the start / stop buttons. In simple terms, you push the start button which energises the coil, this pulls in the contactor which then provides power to the coil to hold the contactor in. The stop button is in series with the coil, so if pushed breaks the coil supply and the contactor drops out. In your case Z is live, will go to the stop button, out to the start button and then the coil, the other side being neutral.

Thanks, that makes sense it’s the control circuit I seem to be missing

looking closely I can see what the start switch on the box is acting on but not the stop, it seems to just float.

Went with Eaton as Spark who wired workshop rates their stuff, if I need to goback to the shops any links for what I need?

cheers for the help!

 

[--Tom--]

Another pic

 

[porker]

That can be used on a 3 phase or single phase motor. (The sticker on the side confirms this). Only need to wire the supply, motor and "connect cable" and link for the coil. There is no other connection required. The 'control circuit' is internal and not something you need access to.

The "connect cable" just allows config to control a 3 phase or single phase motor

 

[Spectric]

Hi Tom

This would be so much easier if I was hands on, so much harder from a distance working from a diagram.

The picture shows a complete DOL starter that requires no external controls unless one has a specific requirement. Iooking at this diagram something looks wrong, why that link marked as "CONNECT CABLE" because it just places another set of contacts in series with the first so no obvious reason. I can see why you are having issues, also one end of the coil looks like it just ends at that point marked N near terminal 5 so it would not function so there are issues. Will look further tomorow and see if it can make more sense.

 

[porker]

I agree that it is a bit strange to use two sets of contacts in series when it looks like this isn't required. The issue with the coil going to N is because this is configurable for a 230V single phase coil or a 380-415V coil. if you look at the bottom diagram in the top left it states the link required between N and 3 for a 230V coil.

All the solid line connections are already in place. All that is required is to make the connections shown in dotted lines and make the link for the coil and it will work.

 

[NetBlindPaul]

You don’t have sn overload in the unit, you need to order it separately. This is normal for an off the shelf dol unit.
95 & 96 are wired in series with the stop button.
Unless the motor has a thermistor I would strongly recommend that you get an overload unit for the equipment.

 

[--Tom--]

Cheers, the internals gives me the starter but the rest of the control circuit is on the overload relay. Just ordered a 1.1-1.6a OL as I worked out FLC to be 1.5a on the motor.

When that arrives all should be fine (crosses fingers it’s compatible)