SkillsUSA preliminary contest Industral Motors Controls Project -- Comments?

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fmtjfw

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Location
Fairmont, WV, USA
The project is to design and build a simple motor control system.

A single-phase motor is controlled by a motor starter using momentary START (green) and STOP (red) buttons. The motor is to be protected from overload by the overload contact of the overload relay If the overload relay tips the indicator light (red) is to be lit.

The motor is single-phase. The motor starter is three-phase. The instruction sheet for the motor starter states that if used for single-phase, all three power contacts and all three poles of the overload relay must have the motor current passed through them.

You need to connect a single pole disconnect between the load side of the motor starter and the motor.

You need to install a GFCI-protected receptacle near the motor.

All metal boxes and the DIN rail the motor starter is mounted on are to be grounded using the green wire from the power fuse box.

The motor is simulated by an ordinary light bulb.
 
don_resqcapt19

don_resqcapt19

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Staff member
Location
Illinois
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retired electrician
fmtjfw said:
We supply IEC starters for the contest and provide a "tour" of an IEC starter/overload for those taught NEMA only.
Click to expand...
In my world IEC starters are rare. They are great if you use them exactly within their specifications, but many industrial plants tend to push the limits of everything and NEMA starters will stand up to that abuse, while an IEC starter won't.
 
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fmtjfw

Senior Member
Location
Fairmont, WV, USA
don_resqcapt19 said:
In my world IEC starters are rare. They are great if you use them exactly within their specifications, but many industrial plants tend to push the limits of everything and NEMA starters will stand up to that abuse, while an IEC starter won't.
Click to expand...

I my world where the local chapter of the IAEI and the members who organize and carry out the SkillsUSA testing for the electrical trades in area schools individually pay for or get donations, we need to look for affordable devices. The current capital cost for our kit of two motor starter, 6 pushbuttons, rotary switches, indicators, GFCIs, boxes, switches .... is about $210 per student. We are currently setup for 10 motor control students.

My expendables are low, 30--50 ft. of THHN of various colors, wirenuts, grounding pigtails ... so I just donate from my personal stock.

Since many of the venues only have 120V 20A 1-phase circuits, we use light bulbs as "motors". Further we soft start the projects by using a light bulb for the Edison fuse that protects each project, so we're not talking about closing on bolted faults.

The other thing with the IEC electronic overloads, we can set the trip current rather than having a set of heat coils, and we can demonstrate the concept of phase-loss relaying.

I don't know the costs for the residential side of the contest, but I do know their consumables (12-2 12-3 14-2 14-3) , SER, ... is much higher than mine and they are set up for about 30 students.

It's to some extent a matter of money.

If you can get someone to give us 20 identical NEMA motor starters, we certainly accept them.
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
fmtjfw said:
I my world where the local chapter of the IAEI and the members who organize and carry out the SkillsUSA testing for the electrical trades in area schools individually pay for or get donations, we need to look for affordable devices. The current capital cost for our kit of two motor starter, 6 pushbuttons, rotary switches, indicators, GFCIs, boxes, switches .... is about $210 per student. We are currently setup for 10 motor control students.

My expendables are low, 30--50 ft. of THHN of various colors, wirenuts, grounding pigtails ... so I just donate from my personal stock.

Since many of the venues only have 120V 20A 1-phase circuits, we use light bulbs as "motors". Further we soft start the projects by using a light bulb for the Edison fuse that protects each project, so we're not talking about closing on bolted faults.

The other thing with the IEC electronic overloads, we can set the trip current rather than having a set of heat coils, and we can demonstrate the concept of phase-loss relaying.

I don't know the costs for the residential side of the contest, but I do know their consumables (12-2 12-3 14-2 14-3) , SER, ... is much higher than mine and they are set up for about 30 students.

It's to some extent a matter of money.

If you can get someone to give us 20 identical NEMA motor starters, we certainly accept them.
Click to expand...

I can understand the cost constraints...that and the smaller size are among the main reasons IEC starters are used.
 
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