Hello,
As a mechanical engineer moving into the automation world i have a few simple hardware questions for the more electrically inclined than I. I have a conveyor project aimed at becoming one subject of an automation project for students. It was donated to us by a local factory and will be controlled by a Siemens s7-1200 series cpu. The conveyor is driven by a 3phase Motor with no plans for vfd, just contactors controlling the forward and backward directions. I'm overseeing a couple interns who are working On developing a small control cabinet. My questions:
1) the s7-1200 has dc 24v supply voltage, which means we need an extra power supply from 220v to 24v. We have some ps307 5A power supplies laying around. Is there a General rule for calculating the power supply amperage required for a specific plc setup and i/o setup? The motors will be switched On and off by contactors, and there are a few electropneumatic solenoids and lights.
2) How do you size circuit breakers properly for a 3 phase motor? We have a bunch laying around for this purpose, but want to be sure they are right for the application.
3) i was told by a colleague that the voltage coming into the control cabinet is usually 480v or something like this and is stepped down to control voltage. Does this take place within the control cabinet generally by a step-down transformer, or does it take place outside of it?
4) besides circuits breakers and contactors, are there any other components i should have in the motor circuit? We have a switch somewhere that I was told sums current flowing in and out of the motor, then trips if there is significant leakage. Should something like this also be in there?
5) how do i size the contactors for the motor to make sure nothing gets damaged by inrush current when switched on?
I'm thinking these are pretty rudamentary questions, but I'd really appreaciate any help from the experts On the board.
Thanks!
As a mechanical engineer moving into the automation world i have a few simple hardware questions for the more electrically inclined than I. I have a conveyor project aimed at becoming one subject of an automation project for students. It was donated to us by a local factory and will be controlled by a Siemens s7-1200 series cpu. The conveyor is driven by a 3phase Motor with no plans for vfd, just contactors controlling the forward and backward directions. I'm overseeing a couple interns who are working On developing a small control cabinet. My questions:
1) the s7-1200 has dc 24v supply voltage, which means we need an extra power supply from 220v to 24v. We have some ps307 5A power supplies laying around. Is there a General rule for calculating the power supply amperage required for a specific plc setup and i/o setup? The motors will be switched On and off by contactors, and there are a few electropneumatic solenoids and lights.
2) How do you size circuit breakers properly for a 3 phase motor? We have a bunch laying around for this purpose, but want to be sure they are right for the application.
3) i was told by a colleague that the voltage coming into the control cabinet is usually 480v or something like this and is stepped down to control voltage. Does this take place within the control cabinet generally by a step-down transformer, or does it take place outside of it?
4) besides circuits breakers and contactors, are there any other components i should have in the motor circuit? We have a switch somewhere that I was told sums current flowing in and out of the motor, then trips if there is significant leakage. Should something like this also be in there?
5) how do i size the contactors for the motor to make sure nothing gets damaged by inrush current when switched on?
I'm thinking these are pretty rudamentary questions, but I'd really appreaciate any help from the experts On the board.
Thanks!