3 Phase Extension Cable

[sull]

Hi, I am a non electrician who desperatly seeks some advice, your help would be truly appreciated.

I am installing some equipment outside, near water which is approximatly 100m from a plant room. The outside area between the plant room and the equipment is is accessable by the public. The equipment operates: 480v 3 phase, 25amp, 60HZ, 7.5KW WITH 2880/133 REVOLUTIONS PER MINUTE. tHE PLANT ROOM CONTAINS 3 PHASE.

I unsderstand that traditionally permantly installing 3 phase supply is very expensive, can I hook up an extension cable obviously this is no normal extension cable and I would like to understand the equipment required and cost involved - I will NOT be doing this myself but I am trying to identify if this is possible and a likely cost - this could make or break the project.

I am extreamily grateful for your help

Kind Regards

Scott

 

[AAAMUSEMENTS]

I think the first question that needs to be asked is, will the equipment be permanent or temporary? That will make a difference I reckon.

 

[sull]

HI, The equipment will be installed throughout the summer and removed in the winter. I am happy to remove the extension each eveneing. Thank you

 

[AAAMUSEMENTS]

You might get away with an armoured 3-phase extension cable. I know these are available from hire shops so you must be able to buy them or have them made.

But I don't know for certain, so I am going to bow out at this point and let one of the properly qualified guys give you a proper answer!

:run

 

[Andy™]

you can use SY flex, which is a lot more flexible than SWA.

100mtr of it isnt going to be cheap either.

also, is it really 60hz?

 

[sull]

Hi Thanks for your input, I can confirm the details of the equipment, copied straight from the brochure:

Electrical Requirements

480 V 3phase, 25amp service, 60 Hz

7,5 kW with 2880/ 133 revolutions/min

Would you know the specifications of the cable and what ancillery equipment would be required.

Many Thanks

Scott

 

[matt.leung]

have a look at:

White light, stage electrics, PRG, etc.. thet are all hire companies that stock 3ph cable for hire. Comes complete with plug and socket at either end....

 

[kme]

The BIG issue here is the 60hZ requirement - if that is necessary, then you need more than just an extension cable. As Andy suggested, SY would be my suggestion; possibly with a SWA supply to somewhere nearer?

But if you do NEED 60hZ supply - there is the biggie problemie. You`ve only got 50hZ - and frequency conversion isn`t going to be cheap!

480V / 60hZ ? That is a foreign supply characteristic; you cannot safely operate that on a 400V / 50hZ.

Maybe cheaper to try and get a genny that can deliver that output; though that isn`t likely to be cheap, either.

Sorry

KME

 

[sull]

This sounds expensive, I know of someone in a remote area who needed a generator as there was no phase 3 available and has spent

 

[kme]

The concerns are both the frequency AND voltage - our three phase is lower voltage.

You could get the motor replaced, but, without knowing anything about the machine in question, guesstimation is next to impossible.

I understand your point about the 3 phase 100M away - but, as it stands, its "the wrong three phase".

IF you changed the motor, and there were no other concerns (sidewinder will be in later - more his territory, TBH), then, for a 100M SY lead, to buy:

about

 

[sull]

This is great information - thank you.

I will go back to the supplier and see what is possible.

Once I find out I am sure I will have another question.

This is a great forum!!!

Have a good weekend

Scott

 

[Andy™]

You mention that 60khz is an issue - what would be acceptable and is there any questions I should ask the supplier which would help.

60hz motor on a 50hz supply will self destruct.

 

[batty]

[quote name='Andy

 

[kme]

That much hertz will killahertz it!

or, Mrs. KME`s version: that much hertz will bring tears to its eyes............

 

[Andy™]

Are you saying it will really hertz.

yes. it will hert really bad. to both user & motor

 

[Badger]

[quote name='Andy

 

[Apache]

Does anyone have a second to explain to me why a motor running at 50Hz rather than 60Hz would self destruct and not just run slower?

 

[Badger]

sorry patch, not my area of expertise, i dont do motors tbh

 

[Andy™]

Does anyone have a second to explain to me why a motor running at 50Hz rather than 60Hz would self destruct and not just run slower?

not an expert with motors, but ill try and answer

iirc is something about the motor runs slower (since speed is directly related to frequency), and therefore has less torque/power. which then makes it run slower. there is then less back EMF and current increases. meaning the it gets hotter. but as its spinning less than designed, the fan spins slower and the motor has less cooling ability, and gets even hotter, and then starts to self destruct.

 

[Sidewinder]

Guys,

A 60Hz motor on 50Hz will NOT self destruct.

Unfortunately once again the VET has it right.

I used to be involved with machine design where we used to spec 60Hz motors for 50Hz supplies to get the required rotational speed without any jiggery pokery (inverters etc.!)

OK, not happy with 400V ext. lead in public area.

Would need to be armoured or SY, if SY I would say additional protection, such as one of those rubber cable covers you see in offices/on roads.

Also I would want front end RCD sorry, just IMHO.

Next, VERY unusual to see 60Hz on German kit their mains is 50Hz.

It is our transatlantic fellows who use 60Hz.

Historical reason and no other to do with the