Control Cabinet Review - Opinions?

[Jieve]

Ahh, I see, just re-read your Post. Makes Sense now, is class 10 a motor circuit specific class designation or what does it mean exactly?

 

[kamenges]

This is copied from the Siemens protection equipment reference manual referring to the 3RV10 devices:

Short-circuit protection​

If a short-circuit occurs, the short-circuit releases of 3RV1 motor starter protectors isolate the faulty load feeder from the network and thus prevent further damage. Motor starter protectors with a short-circuit breaking capacity of 50 kA or 100 kA are virtually short-circuit resistant at a voltage of
400 V AC, since higher short-circuit currents are not to be expected in practice.​

Motor protection​

The tripping characteristics of 3RV10/3RV11 motor starter protectors are designed mainly to protect induction motors.
The motor starter protectors are therefore also referred to as
motor-protective circuit breakers.
The rated current​

​

In of the motor to be protected is set on the setting scale. Factory setting of the short-circuit release is 13 times the rated current of the motor starter protector. This permits trouble- free starting and ensures that the motor is properly protected.
The phase failure sensitivity of the motor starter protector ensures that it is tripped in time in the event of a phase failure and overcurrents that occur as a result in the other phases. Motor starter protectors with thermal overload releases are normally designed in accordance with trip class 10 (CLASS 10).

Keith​

 

[kamenges]

Fron the same document:

Trip classes​

The trip classes of thermally delayed trip units are based on the tripping time (​

​

tA) at 7.2 times the set current in cold state (excerpt from IEC 60947-4):
• CLASS 10A: 2 s < tA < 10 s
• CLASS 10: 4 s < tA < 10 s
• CLASS 20: 6 s < tA < 20 s
• CLASS 30: 9 s < tA < 30 s​

The motor starter protector must trip within this time!

For some reason I can't link to the document. It is listed as document LV1T_051 on the Siemens website.

Keith

 

[DwSoFt]

since this is for students to learn from, another thing to include is a run status and a fault status back into the plc for each motor, just an extra contact on the starter for run and on the overloads for fault. that way you can have them write the logic to address what to do when things dont work as they should.

its one thing to write logic that makes everything work. but you also have to teach what to do when everything doesnt work as it was supposed to.

in addition to that, i suggest maybe getting an electrician involved with this project if possible. he could help you with the design of the cabinet(s) but more importantly, u should have someone knowledgeable in plcs make a program for it first,to make sure it all works as intended and is possible before you ask students to do it?? or if you you were going to write it, thats ok too. id just hate to see students trying to do the impossible.

 

[Jieve]

Thanks again for the responses. I quickly browsed over the Siemens website for the same protectors but rated for the proper motor amperage, and some of them have auxillary contacts as well, One NO and One NC. I'm assuming that these could be used for faults and run condition, if they open/close under the tripped or switched off condition. I will test the One we have tomorrow. We also have a nice flashing red light mounted On the conveyor to indicate a fault condition.

Most of my co-workers are electrical engineers but pulling them away to get them to spend Time On this is tough, for that reason i'm really appreciative for the help. I'm familiar with the programming, so will write a program myself first once everything is complete before setting the students loose. As a mech E, it's the hardware I'm still trying to get familiar with.

Thanks again!