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How does the RPM of a shunt excited DC motor vary as a function of armature voltage, load torque, and field excitation?
How does the RPM of an induction motor vary as a function of input voltage, frequency, load torque, and rotor resistance?
How does a Simpson 260 meter read AC voltage? What is the significance of this method?
What does RMS mean? Why and when is it necessary to use an RMS meter?
Discuss the difference between a volt-ampere reading and a power reading and when is this important?
A wire is strung up in the air and has a normal Amprobe meter clipped around the wire. This wire is well insulated and there is nothing near it or the meter. It is at a potential of 25,000 V with 10 A flowing thru it. You have a telescope and are at a safe distance from this wire. Can you make a safe reading?
Describe how a straingage load cell works? Is this any different than a straingage torque transducer?
How is an LVDT constructed? And how does it work?
Ask them to draw at least one circuit for a two button anti-tie down function?
In a series circuit of a battery, switch, resistor, and inductor how does the current change following closure of the switch assuming the current was zero in the inductor at the time of closure? After steady-state is approximately reached what happens when the switch is opened? Next put a neon bulb with a series current limiting resistor in series with the neon bulb across the first resistor and inductor. Make the battery 120 V. What does the neon bulb display before switch closure, while closed, and after the switch opens? Why is the resistor needed with the neon bulb?
In a series circuit of a battery, switch, resistor, and capacitor. How does the current vary after closure of the switch and how does the capacitor voltage vary?
How does the RPM of a synchronous motor vary as a function of voltage, frequency, and torque? How does the power factor of a synchronous motor vary as field excitation is changed?
Provide a couple portions of a machine tool PLC diagram and ask for a discussion on what the logic does? Something with a holding contact from the coil, a transitional contact, and several series and parallel paths. Include labels and IO addresses for them to reference.
Describe the truth table for an exclusive OR function and ask for a relay contact circuit to perform this function.
Provide a data sheet for some particular timer and ask how to use this to perform an off delay function.
Provide some of the three phase circuits you mentioned and ask various question about these.
Take one of your control panels, create a problem in it, and have the applicant troubleshoot the problem. I see no problem with assisting the person with information with which they may not be familiar, but primarily this would be to evaluate how they would approach the problem.
Create questions from your own experience.
From your questions you want to discover whether the person has adequate background, can they learn on their own, do they have a driving interest in your type of work, can they tolerate pressure, can they grow in the job, can they work independently, can they contribute, or is their major interest to play cards in the shop during the week so they can get overtime on the weekend.
Watch how the person walks and the questions asked while you give a plant tour.
An entry level usually does not mean that that person will always be a bulb changer. Many CEOs started in the mailroom.
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