Industrial Floor Sander not getting enough current?

[Mark Hughes]

I have an at my local scout group. They have employed a company to sand & varnish their hall floor. the company is using a couple of Lagler Hummel machines 230v 50Hz each requiring a 16A supply. (as a screenshot).

A 16A fused socket has been connected to the hut ring main (by replacing a faceplate) to bypass the need for a 13A plug. This was tried but obviously, the startup current blew the 13A fuse.
With both of the machines, they start but the bag refuses to inflate (only one machine tried at a time). The company suggested this was a supply issue..

A separate 16A socket supply was then configured from the consumer unit, from a different phase, using what would have been the cooker circuit but the issue persisted.

The scout group then borrowed a 5KVA generator and again the problem exists. Post the generator test you would assume that the issue was with the machine.. but there are 2 of them identical.

Anyone any thoughts or seen this behaviour before and can provide any pointers?
The company is adamant is not their machines - they were fine on their last job a couple of days ago!

 

[Mark Hughes]

Makes no sense, frankly. You're seeing a volt drop on start-up that's still 8v HIGHER than nominal. Also - do the maths - you're losing 10v at only a maximum of 16A?? That's a massive resistance. Also, you've not said anything about circuit overload protection kicking in which suggests that the issue isn't current.

Without wishing to sound condescending, are you sure the machines don't have some sort of transport locking pin still in place that's simply not allowing them to spin?

I've asked questions around the machines but nothing obvious or sensible from the operators that imply they are doing anything out of the ordinary. I see no logical reason but two machines not working.. Got to be something quite simple either machines or a fault. Not sure if a N fault on the supply side would manifest itself like this given the issue is consistent across phases; I've try and get down to check Ze & Zs but if it's a fault I can't see why it can be anything other than DNO side.

 

[James]

I have come across things like this before where seemingly identical faults appear on 2 different machines.
sometimes it’s a common extension lead or a trailing socket has damaged the plugs on both machines etc.

if you have provided a socket that is showing 220v or higher when under load, the fault is between the point of measurement and the sanding disk.
again, it needs a person on site that knows how to test systematically

 

[Rockingit]

I've asked questions around the machines but nothing obvious or sensible from the operators that imply they are doing anything out of the ordinary. I see no logical reason but two machines not working.. Got to be something quite simple either machines or a fault. Not sure if a N fault on the supply side would manifest itself like this given the issue is consistent across phases; I've try and get down to check Ze & Zs but if it's a fault I can't see why it can be anything other than DNO side.

Z tests will tell you nothing (except possibly a loose connection in a neutral, which may explain the Vd) and you'll still have two dead machines. You are definitely missing a piece of the jigsaw here and in danger of over-thinking things.

 

[Mark Hughes]

I have come across things like this before where seemingly identical faults appear on 2 different machines.
sometimes it’s a common extension lead or a trailing socket has damaged the plugs on both machines etc.

if you have provided a socket that is showing 220v or higher when under load, the fault is between the point of measurement and the sanding disk.
again, it needs a person on site that knows how to test systematically

James thanks; Agreed I need to be there to see for myself. The downside is the contractor is looking to walk away from the job.

 

[Lucien Nunes]

Ze and Zs aren't hugely relevant because the integrity of the earthing doesn't make any difference to whether the machines work. It's Zp-n that you want to know. A high resistance on the neutral serious enough to stop the machines working would probably cause other effects with lights and appliances interacting and possibly failing, because when one P-N voltage goes down, the others go up. A localised high resistance e.g. bad connection, as opposed to an excessively long thin circuit, would tend to overheat under load.

Could you please explicitly confirm that the 238V mentioned in post #6 is measured L-N on the circuit with the machine operating?

Post crossed with various others saying the same thing. Must type faster.

 

[Rockingit]

Just a thought....... have you actually checked the data plates on the machines?

 

[Mark Hughes]

Ze and Zs aren't hugely relevant because the integrity of the earthing doesn't make any different to whether the machines work. It's Zp-n that you want to know. A high resistance on the neutral serious enough to stop the machines working would probably cause other effects with lights and appliances interacting and possibly failing, because when one P-N voltage goes down, the others go up. A localised high resistance e.g. bad connection, as opposed to an excessively long thin circuit, would tend to overheat under load.

Could you please explicitly confirm that the 238V mentioned in post #6 is measured L-N on the circuit with the machine operating?

Yes it was; The first attempt replaces a 13A faceplate on a confirmed 'ring' in the main hall. They attached a 16A commando socket into the back of the socket to test and the voltage was measured there.

They then tried the same test using the cooker circuit from the kitchen (on another phase) with similar results although i don't know the Vd for the test using the Kitchen cooker cct.

 

[Lucien Nunes]

OK fine so the voltage is in the ideal zone 3% above the nominal 230V, and well within the +/- 10% that all machines should tolerate. How can they claim this is inadequate?

I appreciate that it might briefly drop below this during starting, but once it has stabilised at 238 the machine should be fine. It's hardly believable that there is some elaborate function that requires it to attain full speed within a critical time period that would prevent it then functioning once the voltage has increased.

Machines such as this are used on construction sites with long rambling temporary installations, often with significant voltage drop in 110V CT-E circuits. The manufacturers would be aware of this and of the significant starting current, and would not design a machine that could not operate under reasonably anticipated conditions.

 

[Rockingit]

As I've said already, this is classic Ockham's Razor territory and something/body isn't telling the truth somewhere. Simplest thing to do here would be to take a machine home and plug it in there!

 

[Mark Hughes]

are of this and of the significant sta

I have an at my local scout group. They have employed a company to sand & varnish their hall floor. the company is using a couple of Lagler Hummel machines 230v 50Hz each requiring a 16A supply. (as a screenshot).

A 16A fused socket has been connected to the hut ring main (by replacing a faceplate) to bypass the need for a 13A plug. This was tried but obviously, the startup current blew the 13A fuse.
With both of the machines, they start but the bag refuses to inflate (only one machine tried at a time). The company suggested this was a supply issue..

A separate 16A socket supply was then configured from the consumer unit, from a different phase, using what would have been the cooker circuit but the issue persisted.

The scout group then borrowed a 5KVA generator and again the problem exists. Post the generator test you would assume that the issue was with the machine.. but there are 2 of them identical.

Anyone any thoughts or seen this behaviour before and can provide any pointers?
The company is adamant is not their machines - they were fine on their last job a couple of days ago!

The moral of the story - trust your first instincts and ensure the contractor has checked and unblocked his machine!
Thanks for all who replied to my original post.

 

[Yozza19]

Had a similar issue on a construction site with two paint spraying machines turned out they had been imported from America and some wise man had just fitted uk plugs

 

[GBDamo]

I have an at my local scout group. They have employed a company to sand & varnish their hall floor. the company is using a couple of Lagler Hummel machines 230v 50Hz each requiring a 16A supply. (as a screenshot).

A 16A fused socket has been connected to the hut ring main (by replacing a faceplate) to bypass the need for a 13A plug. This was tried but obviously, the startup current blew the 13A fuse.
With both of the machines, they start but the bag refuses to inflate (only one machine tried at a time). The company suggested this was a supply issue..

A separate 16A socket supply was then configured from the consumer unit, from a different phase, using what would have been the cooker circuit but the issue persisted.

The scout group then borrowed a 5KVA generator and again the problem exists. Post the generator test you would assume that the issue was with the machine.. but there are 2 of them identical.

Anyone any thoughts or seen this behaviour before and can provide any pointers?
The company is adamant is not their machines - they were fine on their last job a couple of days ago!

My god, that is almost identical a story to one I witnessed on Tuesday, this one a concrete planer.

(Not my job, I was observing whilst wrangling some singles spaghetti on a scaffold.)

The planer was run via a 5KVA transformer, originally, of a 13A plug.

Blew the fuse in the plug, I changed the fuse for them and clamped it maxing out at 21A, blew a second fuse in short order.

I suggested the machine was Donald but the hire shop said its fine and there was an issue with the power on site*, so the sent over a 5KVA genny.

Genny rigged up, machine just stalled out the moment it touched the floor, they soldiered on and blew the genny after 15 minutes.

The similarities to the OP are astounding.


*this was in a commercial lock up with a 50A TP supply, brand new. Nothing in the board (as I'd ripped everything out) appart from one double socket directly below the board on a C20 RCBO.

 

[Fazz711]

We had similar problems at work with scarifier.
The OPs were starting it engaging with the floor.
Turns out it needed to be tiped back and upto speed before it was engaged with the floor.
If engeged straight off it would overload and trip breaker it thr DB or tripped the trany

 

[freddo]

We had similar problems at work with scarifier.
The OPs were starting it engaging with the floor.
Turns out it needed to be tiped back and upto speed before it was engaged with the floor.
If engeged straight off it would overload and trip breaker it thr DB or tripped the trany

I did wonder if that was the issue here, these appliances are quite aggressive.

 

[Fazz711]

I did wonder if that was the issue here, these appliances are quite aggressive.

With the concrete scarifier flat on the floor it was to much draw.
If you took the load off they worked fine.