Anyone know of a good test to give technician at interview?

Hi all,

Some of the latest people we've been recruiting as "multi-skilled electricians" have been absolutely terrible at grasping PLCs.

We don't test potential new employee's on their PLC skill (or even their ability to learn PLCs).

I would like to devise a few tests that we could give to interviewee's to see if they have the right stuff to work with PLCs.

We're not bothered if they have no experience of PLCs but we just want a simple way to test if they have the right type of logical, fault-finding brain in order to be able to pick it up.

Over the last couple of months we've had a couple of new employee's who, despite lots of training and our best efforts, might as well be door stops.

Any ideas?

Thanks

;-)

Stick a piece of paper under one of the connecting pins on a rack module

Hi HJTRBO, thanks for the suggestion.

I really want more of a hands-off test. I'm expecting people to apply for the job who may not have worked with PLCs in the past.

I want someway of seeing if they have the 'ability' to work with PLCs. i.e. to test their fault-finding / logic solving ability.

Our site is becoming more and more technical. Gone are the days that we needed electricians to just go around resetting breakers etc. We are now looking for electrical staff to diagnose faults via information gleaned from touchscreens and the PLC and to also suggest ways to make our process better.

We can check if a prospective employee has the necessary electrical qualifications. We ask if a candidate has PLC experience and just get a feel for them that way. Unfortunately, they may say they have experience but then, when it comes down to it, they may really struggle with anyting technical and with retaining the information they are taught.

What I would like to do is have some form of written test or puzzle or brief assessment I could give them to see whether they are suitable for our site.

I can probably dream something up but I would have thought that there would already be something out there that people use?

Any/all ideas welcome ;-)

You say lower level... Maybe ask them about what they think about connecting a npn sensor to a digital input module designed for a pnp style sensor. Dont prompt them them or give them clues about using a relay or other connection methods or whatever. You know for the 2am fudge it to get it going.

Yep, that's a good suggestion for a question. Thanks ;-)

I am assuming that the person you want to interview shall test and commision machines, not be a PLC programmer.

Define a theroretical fault condition (i.e. PLC output defective), and find out how the fault would be indicated in real life (i.e. an actuator does not move).
Then show both electrical and mechanical diagrams to the interview person, tell him that the actuator does not move when the PLC output activates.
Ask the interview person "list as many possible causes that you can imagine". 10 possible causes is barely acceptable, 15 is good, 20 is top class.
Ask the interview person how he/she would go about pinpointing the cause.

Also ask if some of the causes he imagine, can be caused by another fault.
I.e. that the actuator does not move, because a circuit breaker is tripped, is actually because a cable has become damaged causing a short circuit.
This is the difference between merely fixing something temporarily, and fixing it for good.

Do that for 2-3 possible scenarios.

Jesper has a nice one, only change I'd make is not saying: "tell him that the actuator does not move when the PLC output activates", but in stead saying: "tell him that the actuator does not move when it is supposed to".

In the first you've clearly established that the problem situates from the output on.
Using the latter, the problem can originate from sensor/input issues.

In a real life situation, that's what he's going to get as information: It doesn't work, that thingy, it doesn't move when it should move.

It is up to them to discover if the output gets activated or not.
Ask em which questions they'll ask the operators, and why.
And how they'll proceed with the information received.


Wish they'd do nice questions like that over here.
Here they rig a machine and tell the interviewee to get it running again. Usually smaller problems, but the fact that it's mostly friends/acquaintances of employees doing the tests, usually they already know where to look. Happens when you use the same test over and over and over.

Great suggestions there. I really like the "list as many possible causes" idea.

I'd also like, if possible, some puzzles that require logic and a good fault-finding thought process but that are generic so that anyone can take them.

i.e. They don't need to have an industrial background to do them. They don't need to know what an solenoid is or what a sensor looks like.

We have some very young apprentices that we sometimes train and if I could find a test that simply checks that they have the right 'mind' to do the job then that would be very handy.

Thoughts?

Thanks for all the great help so far. ;-)

Jeebs said:

Jesper has a nice one, only change I'd make is not saying: "tell him that the actuator does not move when the PLC output activates", but in stead saying: "tell him that the actuator does not move when it is supposed to".

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I am assuming that the starting point is that an error message has been indicated on the HMI and this will only happen if the PLC output has activated. And I also assume that it has been established that the actuator really does not move. This is the typical real-life scenario when the operator (= cleaning guy promoted to operate a plant worth 100M€) decides to call maint.

uptown47 said:

We're not bothered if they have no experience of PLCs but we just want a simple way to test if they have the right type of logical, fault-finding brain in order to be able to pick it up.

Click to expand...

Why spend time/effort attempting to train people with no experience - your minimum entry requirements should be people with plc experience. Whowever is doing the interview test must know the topic to be able to judge the candidate.
I use my first Xmas flash Q0.0 puzzle - people are either reduced to quivering wrecks wondering if they know anything at all about (Siemens) plcs when nothing comes up in the cross reference, or they start wading about in the code determined to find out what is going on. Of course no one is going to solve one of those puzzles in a couple of hours in an interview situation, but you do gain an insight into their problem solving skills.

Make it tough, you want the best.

L D[AR2 said:

Make it tough, you want the best.

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I hear you but we really struggle finding (good) people to work here. We are based in Scotland and the big bucks is with the oil industry. Our HR team seem to just be interested in hiring someone who is an "electrician" as they think that is all our craft population do.

Those days of being able to maintain a full production line without any PLC knowledge are long gone.

If I set a really tough question in the interview then I don't think I would find anyone to fill the roles. That's why I'm thinking of finding a balance and looking for people who are diamonds in the rough. They may not have much (if any) experience but they have those great qualities that anyone who's decent at fault-finding / PLC programming etc has. That spark, the tenacity, initiative, dogged determination, hunger for knowledge, stubbornness that a fault won't beat you etc etc...

I think I can recognise this in someone but I can't be there for every interview and, when I am there, I have to stick to a set of pre-written questions so that all the interviews are 'fair and abide by equal rights leglislation'.

What I want to do is create another sheet of questions / puzzles / tests that we can use when interviewing 'electricians' that will help identify the qualities I'm talking about and will be 'fair' because everyone will go through it.

;-)

PS. Can't remember if I've seen your Xmas flash Q0.0 puzzle.. will look it out. ;-)

The 4 lines through nine dots is a good head twister if you have never heard nor seen it before.

Just looked that puzzle up. You're right. It's a good 'un ;-)

It's this one:

http://www.plctalk.net/qanda/showthread.php?t=35801&highlight=sister

If the person is an electrician and you're trying to find their troubleshooting ability, try giving them an electrical schematic with some quite obvious errors and some more subtle errors. See what they can find (and correct) given 5 minutes to review. This way it should be an area they are comfortable and familiar with, yet still shows that they can look at something and think about it, rather then just building it to print.