Softstarter "inside delta" connection. Why only for some kind of softstarters ?

[JesperMP]

I have read one mention of oversizing the soft starter causing a problem

Cant imagine why that can be a problem. We always oversize the softstarters.

today I used the config tools for a safety contactor and found one rated for 300 amps for about $1900 before discount

What is a "safety contactor" ?
The $1900 price sounds about the same list price for a similar Siemens contactor over here, but list prices are more or less irrelevant. Cant tell you how much discount we get, but it is "a lot". Any discount less than 50% means you being grossly exploited.

 

[OkiePC]

Cant imagine why that can be a problem. We always oversize the softstarters.

I agree, I think the concern was related to sizing the motor protection for the starter and not the motor.

What is a "safety contactor" ?
The $1900 price sounds about the same list price for a similar Siemens contactor over here, but list prices are more or less irrelevant. Cant tell you how much discount we get, but it is "a lot". Any discount less than 50% means you being grossly exploited.

We're not very big so our discount is less than 50%, but still pretty significant.

http://literature.rockwellautomation.com/idc/groups/literature/documents/pp/100s-pp003_-en-p.pdf

I believe in the size I am looking at, the "safety" contactor contacts are not force guided, but the auxillaries are "mirrored"...more reading to do in the above link.

 

[JesperMP]

A friend of mine in another company gets 70% (!) from Grp. Schneider.
We dont get that much from Siemens, but it is in the same ballpark.
I have said too much already.

NB. The discounts mentioned here is for low-voltage switchgear, not for PLCs and software which is not nearly at the same level.

 

[JesperMP]

I think the concern was related to sizing the motor protection for the starter and not the motor.

Thermistor protection ! Some of the higher end softstarters have connections for thermistors already. We always spec thermistors for motors that are to be started via softstarters or VFDs.
In addition to that, all softstarters (that I know of) also are intelligent overload relays. Even without the thermistor protection, the softstarter will trip if it calculates that the motor has overheated.

 

[OkiePC]

Thermistor protection ! Some of the higher end softstarters have connections for thermistors already. We always spec thermistors for motors that are to be started via softstarters or VFDs.
In addition to that, all softstarters (that I know of) also are intelligent overload relays. Even without the thermistor protection, the softstarter will trip if it calculates that the motor has overheated.

Yes, I am a big fan of thermistors too, but I don't get to spec the motor in this case. However, when it comes to replacement parts (hopefully many years from now) I will try to insist on them and have the spares in my control wiring ready to go. The SMC Flex does have dedicated "PTC" inputs and asociated alarms/faults/parameters.