Hi current load at switch on. Planer Thicknesser

[pe2dave]

I've had a Sheppach hms260 PT for some time now. It blew fuses infrequently, the manual stated 16A slo blow fuse.

Started blowing them regularly last winter so I've just had a 16A feed put in. Whilst the electrician was here I asked him to monitor the startup current.

He did, with a digital clamp on ammeter. I was .... quite gobsmacked when it averaged out at 38A peak reading. Admitted it's likely to be only for a few milliseconds, but it still astounded me.

Unloaded running current was nearer 3.5A.

 

[PeterBassett]

It's got a big heavy steel cutter block to spin up and all the roller mechanism etc.

38A though, blimey.

 

[Peter T]

Sounds about right.

Startup inrush can be up to 10 times no load running current.

 

[Dibs-h]

I've had a Sheppach hms260 PT for some time now. It blew fuses infrequently, the manual stated 16A slo blow fuse.

Started blowing them regularly last winter so I've just had a 16A feed put in. Whilst the electrician was here I asked him to monitor the startup current.

He did, with a digital clamp on ammeter. I was .... quite gobsmacked when it averaged out at 38A peak reading. Admitted it's likely to be only for a few milliseconds, but it still astounded me.

Unloaded running current was nearer 3.5A.

That's why a lot of folk recommend a certain class of breaker (C or D - I can't quite recall) for workshop supplies where there is kit like that on it.

 

[9fingers]

Dedicated 16/32 amps supplies for motor use should use a type C MCbs to minimise nuisance tripping on start up.
Other circuits should use a standard Type B MCBs

Bob

 

[pe2dave]

Dedicated 16/32 amps supplies for motor use should use a type C MCbs to minimise nuisance tripping on start up.
Other circuits should use a standard Type B MCBs
Bob

Type C being? Any uri on information or purchase please?


Dave

 

[9fingers]

All MCB manufacturers will offer type C breakers. They look just the same as type B (but are marked type C).
Any electrical dealer will know about these.
Usually it is best to get the breakers of the same make as your consumer unit as not all makes fit all CUs.
Bob

 

[pe2dave]

Dedicated 16/32 amps supplies for motor use should use a type C MCbs to minimise nuisance tripping on start up.
Other circuits should use a standard Type B MCBs
Bob

Type C being? Any uri on information or purchase please?


Dave

From http://is.gd/dvx1c

* Type B devices are designed to trip at fault currents of 3-5 times rated current (In). For example a 10A device will trip at 30-50A.
* Type C devices are designed to trip at 5-10 times In (50-100A for a 10A device).
* Type D devices are designed to trip at 10-20 times In (100-200A for a 10A device).


So my 38A surge would be comfortably within the 10* surge allowed
for in the 16A MCB.

 

[9fingers]

I can't remember the details but the key difference between the classes is the time taken to trip at n x the rated current. All types will give similar long term tripping currents but type c and D will withstand the higher current for greater durations thus allowing time for motors to start however if there is a fault, they will still trip before risk of fire and other damage.

The key function of circuit breakers is to protect the wiring NOT the appliance connected to the circuit.

Bob