NVR Switch

[gidon]

Tony, but for a rough calculation of MAXIMUM possible power a NVR switch could support, not knowing the power factor, P=IV is sufficient. And hopefully good enough to base a buying decision on. Perhaps myself and others should have made it clear we were estimating the maximum power the NVR switch would support, but thought that was implicit.
Cheers
Gidon

 

[Shadowfax]

Got to agree with Gidon as far as rough calculations go. In most cases that should be fine. As far as my original post goes I bought the Axminster NVR switch that Gidon recommended and it works very well with no sign of any problems so I guess my question has been well answered.
Spud, though, seems to have got a flurry of replies but has his actual question been answered?
Me - I got a bit confused somewhere along the line!
Cheers.

SF

 

[devonwoody]

Triton have a saw and router both over 2200 watts, and NVR switch on their table so I expect you can buy their switch as a spare.

 

[Midnight]

is it possible to get both to start and stop using a NVR switch mounted on a router table or wall?

Spud..

what you're asking is not only possible, but straight forward; I'm running a 2kW router from the PTO on my shop vac using an NVR to switch the router. The setup has been trouble free for nearly 3 years now, used on a regular basis, and invariable pushed hard when in use... I'm using the Trend NVR, my only complaint with it being the length of cable on the output side of the NVR is a wee bit short, but workable. Ideally I could have used another half metre for a neater cable run.

 

[Rattie]

Gidon,

That is actually the MINIMUM figure. If you were switching a purely resistive load e.g. a big halogen lamp, then you could equate the power rating of the switch with that of the lamp. The current drawn by the lamp is the limiting factor here, as the switch must pass that current.

Now once you get indictive, the current increases for a given power, on account of it being out of phase with the voltage driving it. Thats why, the electricity companies get all shirty when customers go too inductive - they charge for power, but have to pass huge currents.

If you have switch rated at 2400 Watts load or 10A, then that only holds for a resistive load. Once you start hanging motors off it, then the 10A doesn't get you as much real power in the load, so 10A becomes 2000 Watts or 1500 Watts - thats where the power factor.

I hope that helps get the relevent bits of the theory across. You'll often get away with overloading devices, even for years. But then sometimes you won't, and that's when the magic smoke starts leaking out :wink:

Martyn

 

[ike]

But aren't NVR's designed primarily for switching motors anyway? I've never seem a light switch or heater operated via an NVR. So is it not safe to assume that the rating on an NVR switch for an inductive load - or am I missing the point here?

Ike

 

[Rattie]

As an amusing and almost relevant aside, my lovely new Scheppach HMS260ci is rated with an input power of 2.7kW. If that was 240V x 11.25A, then I wouldn't keep blowing b@st@rd 13A fuses if I have my vac on before powering it up!! But I do.

Thats because the induction motor is very highly inductive as it spins up, so the current goes way up. Grumble grumble. Rewire rewire. Mutter mutter.

Martyn

 

[ike]

But aren't NVR's designed primarily for switching motors anyway? I've never seem a light or heater operated via an NVR. So is it not safe to assume that the rating on an NVR switch is for an inductive load - or am I missing the point here?

(Corrected for appalling typos - brain not connecting with keyboard!)

 

[Rattie]

Ike,

You're absolutely right, most NVR's will be switching motors, and if you look at the specs of the units themselves in say RS, then they'll give you a current rating. Looks like RS do one rated to 16A , whch should cover most people's kit - even my P/T! This is especially true for single phase gear plugged into 13A fused sockets, the fuse will protect the NVR pretty well.

The problem is when a sales type translates the current rating into a theoretical load power rating. If he/she multiplies by the mains voltage, then you get a lousy guess that would as you say be only any good for resistive loads. How much it's out is down to the particular tool you use. Maybe 5%, maybe 20%, who knows?

(I'm sure mine's full of typos too)

Martyn

 

[Anonymous]

So basically, it is possible.

 

[Midnight]

Absolutely....

just don't try to jump start a 747 with the set up and you'll be fine....

 

[Rattie]

Righty ho,

For those looking for some practical guidance, a 10 Amp NVR is considered (by Axminster) to be suitable for up to 1hp (about 800 watts) in an induction motor, or a 1500 Watt brush motor.

Now the original question was about a 2200 W router, so its a brush motor, and I reckon you'd need a 15 Amp rated NVR switch to run it. Sorted, that current rating will be the figure actually printed on the switch, so its easy to tell if you are safe or pushing it.

Hope that helps somebody at least.

Martyn

 

[devonwoody]

I have a 2200watt router (triton) and instead of purchasing a new NVR switch I am running an extension lead from another NVR switched outlet (table saw also 2200watt) using same as a master switch.

Costs of NVR switches for this size equipment could start to mount, if you have 2 to4 pieces.

 

[Anonymous]

Tony, but for a rough calculation of MAXIMUM possible power a NVR switch could support, not knowing the power factor, P=IV is sufficient. And hopefully good enough to base a buying decision on. Perhaps myself and others should have made it clear we were estimating the maximum power the NVR switch would support, but thought that was implicit.
Cheers
Gidon

Gidon

Why would not knowing the difference between AC and DC power appear implicit?
I do not believe that the people posting their calcs were aware of the true formulae for AC power (or necessarily that it is different to DC power calc) and thus posted info to help out.

 

[gidon]

Tony
Sorry - got a little defensive . I found your posts infomative - been a while since I've thought much about that sort of stuff.
Cheers
Gidon