Plc or Hardwiring

Hi all,

Just need your thoughts.
I'm going to be training another maintenance guy in about three to four weeks. This guy is coming into the department as a "helper". To my knowledge he has taken some basic electricity classes, so that would be about the extent of his training. These helpers are expected to at least be able to hook up to a plc and find the problem,” after training that is". I have always been in charge of this training process, whether it be training a helper or a top paid electrician.
I'm always looking for ways to improve the way I train these guys. I have about 3 months to go over PLC's,HMI,Robots,Low and high voltage wiring and a lot of other things, depending on time. I only go over the basics on each of these things because obviously 3 months is not enough to do just one of them.

I have always sworn by, one should know how to hard wire before they ever touch a PLC. My thoughts are, if they can hardwire some ice cube relays up with some push buttons etc.,then they will have a better understanding of BASIC plc logic. I actually give them projects, where I draw up some schematics and tell them to wire it up. When they have gotten that down, I have them do the same schematic on the plc. I have had in the past, some of them wanting to rush through the hardwiring part just so they can get there little hands on that plc. I've also learned that when they do this they struggle at the plc part. I would like to have your thoughts on whether hardwiring should always come first before we dive into plc's? Is this good practice that I'm doing?

Thanks,
Tim

YES

And at the same time go ahead and explain what your plants' wiring color code is...every plant and every PE seems to do it just a little differently.

And do basic Safety....Good people are hard to find!

David

Personally I think the hardwiring part of it is the most important, the plc is just a device that is part of a system. Anyone involved with industrial electrical...ie machine electrical must understand hardwiring concepts. In many cases the plc will not be at fault, determining that an input or output device is not working is more important. Knowing that when the LED's are on/off when an input/output is activated can go along way in troubleshooting.

Personally in that 3 month period I would probably spend the most time with hardwiring, voltages, drives then move to the plc's, hmi and robots. Without a good solid aunderstanding of the basics they wont grasp the rest.

Naturally each individual is different and if all you have to teach is one at a time that makes the job a little simpler. Have them get their hands dirty in the process, real world apps go along way in explaining things that have only been seen on paper.

A simple example, at my work one of the electricians had been there for 3 yrs when I started work there. In that time he was more or less an assistant to another electrician that was more outspoken. Soon after I arrived the outspoken electrician was moved to nights. In the meantime we were in the process of adding machines to our plant from plants that were closed. The other electrician didnt know anything about a plc or what an Inverter was. I had to show him how to use the LED's to troubleshoot a machine and how to install an inverter. The inverter he got down with one install, has done many since then. The PLC's he still doesnt fully understand but can use the led's to determine if input/output devices are working. My willingness to show him how (for me was selfish reasons, more he knows the less I have to do) these 2 small things have him back in school taking classes. He had a good installation background though so may have been easier to teach than your candidates.

Yes, Tim, that's an excellent approach. Inputs and outputs are usually pretty simple, but many people can't grasp the idea of internal bits, since they can't physically see them.

Therefore, make sure the hardwired relay circuits you give them include relays that aren't directly connected to "the outside world" (PBs, lights, etc.). IOW, relays that are equivalent to internal bits.

Requiring them to build some simple hardwired circuits will also help them really appreciate the benefits of using a PLC rather than hardwiring.

Also be sure to show them how a easily a hardwired relay circuit diagram can be converted to PLC logic.

beerchug

-Eric

Training

What can I say? You are right on.
Just adding my support.
Roger

Definetly agree with everything. So little time so much to teach!

Rsdoran, That is a good selfish reason to teach someone,not only will you have less to do but it makes it easier when you need an extra set of eyes to see something around a corner and they know what you're looking for without telling them.


Drewcrew6

How about analog?

I don't know if you have any analog sensors in your plant, Tim, but if so I definetely reccomend you spend some time with him (her?) on analog sensors, especially 4-20 mA loops. Maybe wiring a sensor and a simple controller with alarms will help. I have an amazing number of instances talking guys through troubleshooting loops over the phone where they have no idea how to measure the sensor output, and at least half my wiring changes on start-ups is reversed polarity on transmitters. Just look at the number of questions this generates on the forum here!

ok, but

I agree, with total newbies, the hardwiring stuff is
really important, since its the wires that do the
heavy lifting, from a practical standpoint.

I've found, in my PLC classes, that non-electrical
types tend to pick things up, initially, faster.
[later on, they get bogged down].

Since a non-electrician is not comparing the logic
to anything he already knows, he doesn't have to
un-learn anything.

Anyone who's tried to explain the --]/[-- instruction
to a seasoned electricial knows what I mean.

Good Luck

"Give a man a fish, he eats today.
Teach a man to fish, he eats forever."

Peace Corps commercial, c. 1960