Msf For 315 Kw Feed Water Pump &315 Kw Id Fan

[gaurav1981]

i have an enquiry for MSF for 315 Kw feed water pump &315 Kw ID fan,with inside delta connection to motor.

 

Customer is also keeping a star-delta starter, as an option if soft starter fails.

 

What i know is that MSF cannot be used for inside delta condition.

 

Then what is the solution keeping in mind that customer wants minimum time taken for him to transfer from softstarter to star delta, in case of any problem with softstarter.

 

Can we divide the output supply from softstarter into two parts( using contactors in these two output partitions) & give them into six leads to motor, with necessary phase reversals, & interlock this arrangement with star delta starter.

 

Will , all the benefits of starting viz. linear & quadratic torque profile valid in this condition , protections.

 

Customer is using above mentioned arrangement for VFDs.

 

Please suggest.

 

Thanks & Regards,

gaurav1981

[marke]

Hello gaurav1981

 

Welcome to the forum.

 

One option is to treat the soft starter exactly as you have treated the VSDs and use two contactors on the output to connect direct to the motor windings.

Another option is to put the soft starter in series with the star delta starter with a switch across the start button so that the star delta starter can be left in the ON state. I would then use an electrical interlock from a NO contact on the delta contactor such that the soft starter can only start when the delta contactor is closed.

 

A contactor or an isolator can be connected across the soft starter to bypass it when you use the star delta starter.

 

I have never used, or considered using the soft starter in this manner. We just connect the soft starter directly to the motor. The soft starters tend to be more reliable than the star delta starters. I have many soft starters in excess of 20 years old and no reliability problems.

 

Best regards,

[gaurav1981]

Thanks for the reply, Marke.

 

The ambient temprature in india is 50 degree Centigrade, therefore i will bypass the soft starter after it has reached full voltage.

 

The configuration I've decided is as follows:

 

Softstarter , c1( bypass contactor) & c2 ( delta contactor). During operation when softstarter is working, c2 is also on, when softstarter is through c1 comes in picture & c2 remains in circuit as delta contactor as before.

 

Star-delta starter : c1( here it will act as main contactor), c2 ( delta contactor), c3 ( star contactor)

a change over switch isolates softstarter & gives supply directly to c1 which now will act as main contactor for star delta , & c2, c3 will function as expected.

 

That is c1 is acting both as a bypass for softstarter & main contactor in star-delta circuit.

Input for delta contactor(c2) will be picked from output of c1.

 

What are your views.

 

I've selected MSF 570 for both feed water pump(315 Kw) & ID fan( 315 Kw)

Do You think , as i'm going for bypass for softstater after it reaches full voltage , I should take rating of msf one step smaller But consider ambient of 50 degree c & also as feedwater pumps have to supply water against steam pressure, & for ID Fan considering damper fully open.

 

[marke]

Hello gaurav1981

 

The way that I understand your description, you are effectively installing the soft starter in the inside delta connection. The MSF is not designed for inside delta operation.

If the star delta starter is wired in the usual format, then the main contactor and the delta contactor both carry winding current only.This means that the main contactor will be too small as it will be rated for winding current only.

 

Best regards,

[gaurav1981]

Dear Marke,

 

I'll try to make it more clear:

 

a) when softsarter along with its dol bypassC1 & C2 for making delta:

 

C1 acts a DOL bypass for soft starter( & its rating is taken accordingly) & comes in picture after softstarter has reached full voltage.

Now C2 is placed on the downstream of the common output of C1 & softstarter( after the Cts for Bypass)

therefore when softsarter was operating , softstarter & C2 were supplying power to motor windings, After reaching the full voltage , softstarter bypassed, C1 & C2 supply power to motor windings.

 

Suppose softstarter is out of order & we have to run the motor through star delta method:

 

Now a change overswitch disconnects C1 from the softstarter bypass circuit( the point which was acting as common input for C1 & softstarter) & connects it directly to mains supply.

 

C2 is already placed at the downsteam of C1( C2 still act as delta contactor, as in a)

C3 is introduced in the circuit as Star contactor.

 

I hope, this is much cleare than what i wrote earlier.

 

Waiting for your views

 

Thanks & regards,

Gaurav1981

[gaurav1981]

Hello Marke,

 

I've understood where i'm going wrong.

 

Some clarification:

 

Star-delta starter has been kept only for the the event of softstarter going out of order.

 

As ambients are high, we need to bypass softstarter after it achieves full voltage.

 

Total 4 contactors, c1 for softstarter bypass & inline contactor for star-delta

 

C2, C3 main & dleta contactor , to be used in both cases , when softstarter is operating( or its bypass)

& also when star-delta is operating

C4 for star in case of star-delta

 

Isolator in incoming & outgoing of softstarter.

 

I hope , it will be fine.

 

Thanks & regards,

gaurav1981

[marke]

Yes. that sounds better, more along the lines of my original suggestion, although I would still get rid of the star delta starter myself!!

 

Don't forget to set parameter 32 ON and also to move the CTs so that they continue to monitor the current once the starter is bypassed. see section 7.12 in the manual.

 

Good luck and best regards,

[gaurav1981]

Dear Marke,

 

Except e-motron , companies like abb, schneider, siemens offer inside delta operation with softstarters.

Siemens & schneider accept in their manuals that for this type of operation some features suach as soft-stop & some protection features are not available but abb does not mention about it.

 

So will it be justified to assume that same happens with abb.

 

Except using a smaller size of soft starter, are there any othe advantage of inside-delta method.

 

What are the disadvantages for the same.

 

I know this is a company specific question but i did not find anything in abb manual about it, have you come across some information about it.

 

Regards,

 

gaurav1981

[marke]

Hello gaurav1981

 

Having been an early developer of 6 wire or inside delta connection soft starters, I would say that in theory, there is no reason why the protection and features should be restricted in six wire connection, however many manufacturers compromise the 6 wire performance by just fiddling the initial firing angles to get the starter to work and as such they do compromise the performance.

Many years ago, I developed algorithms for auto selection of three wire and six wire connections and this reduced the potential for any installation related problems, plus this was supported by different algorithms and code for the six wire operation.

There is another thread on this forum by an operator who has had many problems with inside delta connection, so all is not well in some camps.

 

The prime advantage of six wire connection is that you can use a smaller soft starter to control an induction motor. Correct thermal analysis of the SCR junction temperatures during start show that the starter can be 2/3 of the size. (not 1/rt3 as suggested by continuous sine wave analysis). This is due to the different shape factor of the current waveform seen by the SCRs during start and the resultant junction temperature rise.

 

If you use a six wire installation, you must use a line contactor to disconnect the motor when the starter is not operating, otherwise one end of each winding in the motor is permanently connected to the supply.

 

To correctly design a soft starter for true operation in three wire and six wire connections with all functions working requires a lot more code and development time, hence some manufacturers do not offer this option.

 

You may wish to look at http://www.lmpforum.com/inforum/index.php?...ic=1867&hl=

 

Best regards,

[sapc]

Hi Gaurav,

 

Any service / spare related to EMOTRON products kindly let us know.

 

 

 

Regards

 

sapc

 

 

 

i have an enquiry for MSF for 315 Kw feed water pump &315 Kw ID fan,with inside delta connection to motor.

 

Customer is also keeping a star-delta starter, as an option if soft starter fails.

 

What i know is that MSF cannot be used for inside delta condition.

 

Then what is the solution keeping in mind that customer wants minimum time taken for him to transfer from softstarter to star delta, in case of any problem with softstarter.

 

Can we divide the output supply from softstarter into two parts( using contactors in these two output partitions) & give them into six leads to motor, with necessary phase reversals, & interlock this arrangement with star delta starter.

 

Will , all the benefits of starting viz. linear & quadratic torque profile valid in this condition , protections.

 

Customer is using above mentioned arrangement for VFDs.

 

Please suggest.

 

Thanks & Regards,

gaurav1981