What is the difference between and ac & dc motor on a sectional overhead door at distribution centre?

Question

I work in an organization that services and repairs loading bay doors, dock levellers, scissor lifts & roller shutter doors. I have recently applied for a promotion of sorts but struggle on the electrical side. Any help greatly appreciated.
Thanks

Answer 1

I've been installing, troubleshooting and adjusting high rise elevators for 21 years and still don't know all there is to know about the different motors, drives and control systems whether ac or dc. You won't find the most useful info here on YA as is proved by the previous posts.
My recommendation is to get some basic info from books or search the net. Look specifically for ac and dc motor theory.
The latest technology uses motor controls that utilize Insulated Gate Bi-Polar Transistors (IGBT's) and Silicon Controlled Rectifiers (SCR's) to gain precise speed and torque control of the motors. Step motors are another technology that is being used more often also.
Some more advanced systems use software to get the job done while others use hardware vector and relays to open/close doors.
The bottom line is that there is no easy answer. See if you can get the schematics of some of your companies systems and talk to the installers. You can find info related to the technology they are using and skip alot of the other info that's available.

You will find some very useful info here:

http://www.elexp.com/links.htm

I hope this helps. Good luck on the promotion!

Answer 2

AC and DC motors are generally different beasts with different feeding requirements. AC is used when there is power that you can plug into. DC will be used for battery operated vehicles and scissor lifts.

AC motors come in a variety of types and Wikipedia is the best place to find out what an induction motor is, what shaded pole is and why phase capacitors are used, and how some motors can run on both AC and DC.

Answer 3

AC current (alternating current) is the current that you get when in the mains power sockets. It is produced by a magnet spinning around a coil of wire, which creates a changing positive/negative charge (hence alternating).

DC current (directional current) is produced by things like batteries. The charge is always either positive or negative.

So the difference is just the power source that it needs.

Answer 4

Ac motors are trouble free simple starting st oping arrangement with limit cut in cut off. Motors are connected with gear box to reduce speed.no speed control by electrically.In that same place DC motors are used it required DC supply .It may be from Battery bank or by means of Rectifier ,It is expensive only advantage speed can be varied easily by Armature control or by voltage control.Again Thyristor con trolls are required .This up to your choice which one you are going to chose.I have given you in a simple manner .I t is a big subject pm me if required

Answer 5

just to add to kamran

it is aslo Alternating because it alternates between +180 and -180 degrees, to produce a 360 degree cycle, which produces Voltage.