Help Needed in selecting a Motor Soft Start

r_keates · Jun 27, 2012

Hi all,

I've just completed a 3-phase installation for a Wurlitzer Cinema organ that is being installed into the Troxy (previously a cinema, now a multi purpose venue) in East London.

The next stage of the installation is the design (and eventually installation) of the connection of the large motors which form the massive air blowers that provide the air to power the organ pipes.

We have a limited power supply available (the motor supplies are currently breakered at C40), and the motor specs are as follows:

380-440V AC 3-Phase
15HP
21A Continuous Current

We have 2 of these to install (one for each side of the cinema), and so I need to find a pair of soft starters suitable for handling the starting load, within the limits of the C40 breakers.

Can anybody advise on a suitable unit to carry out this job? I can cope with most things, but i'm not quite as knowledgeable on motors as I would like to be, so I thought it best to ask advice from fellow electricians than spec the wrong product for the job!

Many thanks in advance,

Rob

Guest111 · Jun 27, 2012

Tony,s probably your man just hang about till he pops on,shouldn,t be too long.

Knobhead · Jun 27, 2012

Contact Telemecanique, the reason I say this is:
A/ they are helpful
B/ they are reasonably easy to set up
C/ replacements are readily available (not that you should need them)

One thing to add, put an interlock between the two starters so that fan “A” is up to speed before fan “B” starts. The soft starts will ease the starting load, the delay will ease the total load.

Marvo · Jun 27, 2012

You'll need an 11 kW soft starter for each motor. 11kW is available in some of the compact ranges depending which manufacturer you prefer. You can try Danfoss which are fairly solid kit.

As far as running current goes, the 21Amps, which I assume you got off the motor info plate, is most likely FLA specs. The actual run current will be determined by the load the motor is under so it should be somewhat less than that.

It might even be worth trying the motors without a soft start, you could possible swap the MCB for a D curve and stagger the starts of the motors with a short time delay (a few seconds) on one of them.

Edit; Excuse any repeat info, got beaten to the post by Tony

theroadblock · Jun 27, 2012

Tony said:
Contact Telemecanique, the reason I say this is:
A/ they are helpful
B/ they are reasonably easy to set up
C/ replacements are readily available (not that you should need them)

One thing to add, put an interlock between the two starters so that fan “A” is up to speed before fan “B” starts. The soft starts will ease the starting load, the delay will ease the total load.

I have had many dealings with telemechanique and i must agree their products are not only of high quality/ease of use but the customer support and queries are very good!
Also /agree with the interlock, we use the same method on our *chopfans* at my place of work since they are each ~11kw they are sequencially started to avoid that nasty inrush of all coming on at once

.