Powering a fan

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Beefsmith

Member

• Aug 10, 2019

• #1

We’ve a shed that next year will be used to store grain. It’s got single phase elec in it already for lights etc. We want to put a fan on the back to blowing grain. To get 3 phase we’ve got two options. The first is a 230m dig to install the cable from the nearest board. As the crow flies it’s only 100m but there’s sheds in the way so digging around them creates 230m.
Or a generator? Use would be obviously harvest time so August - September and then it’s sporadic for cooling so we are think no more than 3 months use per year in total but that could be between August and April. It’ll be a 37kw (50hp) fan.

 

Sharpy

Member

Livestock Farmer

Location

Ardrossan Ayrshire

• Aug 10, 2019

• #2

Engine driven fan?

 

U

upnortheast

Member

Livestock Farmer

Location

Northumberland

• Aug 10, 2019

• #3

Hire companies might give a decent deal for 3 month hire
or SH 50 kva genny .
I`m guesing your 230 m cable will be well over £2000

 

D

Doing it for the kids

Member

• Aug 10, 2019

• #4

If you plan to use the store for the forceable future then hard wire every time. I bet in about yr 3-4 the genny hire and fuel will have covered the cable install

 

Mur Huwcun

Member

Livestock Farmer

Location

North West Wales

• Aug 10, 2019

• #5

Can’t you run the armoured cable through the sheds along rafters etc? Huge difference in voltage drop between 100m and 230 which I guess will more than double the size and cost of cable.

 

S

spanners and hammers

Member

Location

cambridgeshire

• Aug 10, 2019

• #6

two fans helps a lot with start up loads and draw ???

 

D

Doing it for the kids

Member

• Aug 10, 2019

• #7

spanners and hammers said:

two fans helps a lot with start up loads and draw ???

Click to expand...

Especially with soft start

 

B

Beefsmith

Member

• Aug 11, 2019

• #8

upnortheast said:

Hire companies might give a decent deal for 3 month hire
or SH 50 kva genny .
I`m guesing your 230 m cable will be well over £2000

Click to expand...

£280/week so far is the best price and we will need a 150kva generator for a 37kw fan according to a local sparky. He said anything less wont start the fan up.

 

B

Beefsmith

Member

• Aug 11, 2019

• #9

Mur Huwcun said:

Can’t you run the armoured cable through the sheds along rafters etc? Huge difference in voltage drop between 100m and 230 which I guess will more than double the size and cost of cable.

Click to expand...

The sheds are all units and walled to the apex so it would mean cutting through bricks and plasterboard as they are offices.

 

B

Beefsmith

Member

• Aug 11, 2019

• #10

spanners and hammers said:

two fans helps a lot with start up loads and draw ???

Click to expand...

Can you explain a bit more please?

 

U

upnortheast

Member

Livestock Farmer

Location

Northumberland

• Aug 11, 2019

• #11

Beefsmith said:

we will need a 150kva generator for a 37kw fan according to a local sparky. He said anything less wont start the fan up.

Click to expand...

Bloody hell. That seems a lot. I would get a second opinion.

If that is right then you will need a beast of a cable for your 230m run

 

S

spanners and hammers

Member

Location

cambridgeshire

• Aug 11, 2019

• #12

Beefsmith said:

Can you explain a bit more please?

Click to expand...

run a pair of 25 hp start them up one after the other fit a baffle door in the tunnel to stop the back pressure then when both up to speed open the door ,,, takes so much off the start up load ,, think from memory start up is 3 times the run amps as stated on the motor

 

Blue.

Member

Livestock Farmer

• Aug 11, 2019

• #13

35mm2 4 core would be about £10/m

Good for over 40kw.

As posted get a 2nd opinion,most sparks go way over the top on these type of things.

 

S

spanners and hammers

Member

Location

cambridgeshire

• Aug 11, 2019

• #14

depending what you want to spent this can all be done auto in the control gear ( soft starts timers and a set of lourves )

 

S

spanners and hammers

Member

Location

cambridgeshire

• Aug 11, 2019

• #15

best to be a little over the top do not want everything on its limits ,, does sound high to me too

 

D

Doing it for the kids

Member

• Aug 11, 2019

• #16

spanners and hammers said:

run a pair of 25 hp start them up one after the other fit a baffle door in the tunnel to stop the back pressure then when both up to speed open the door ,,, takes so much off the start up load ,, think from memory start up is 3 times the run amps as stated on the motor

Click to expand...

Yup I’d agree there. Soft start \ more fans and controls means you can call for the power slowly thus not needing such a big supply

 

TheTallGuy

Member

Location

Cambridgeshire

• Aug 12, 2019

• #17

spanners and hammers said:

run a pair of 25 hp start them up one after the other fit a baffle door in the tunnel to stop the back pressure then when both up to speed open the door ,,, takes so much off the start up load ,, think from memory start up is 3 times the run amps as stated on the motor

Click to expand...

The multiplier factor will depend on motor spec & when running on a genny it will depend on the generator controls/overload control. I have a 5kVA genny that won't start one 650W motor, but will run a 2kW vacuum cleaner motor!

 

Badshot

Member

Location

Kent

• Aug 12, 2019

• #18

Defo use two fans, then if you only use part of the store you only need one fan. And for cooling as well.
You'll need soft starts not star deltas.
Maybe look into the variable run ones so you can reduce the high speed running too if it's not necessary to run flat out.

 

Deutzdx3

Member

• Aug 12, 2019

• #19

Use an inverter if the power supply allows. We run a 10hp screw compressor off one and 2 3kw motors powering a spray booth. Been doing it for 10 years hostel free. Just need the right size cabling and power supply.

 

teslacoils

Member

Arable Farmer

Location

Lincolnshire

• Aug 12, 2019

• #20

Cable. Do it once. Will always be there. Generator are just a pain.