At last, So this IS a new project?
Rather than existing?
Have any of you guys had any Industrial control experience?
Max.

At last, So this IS a new project?
Rather than existing?
Have any of you guys had any Industrial control experience?
Max.

No this is not a new project. The guys i'm working with are more friends than partners. Another friend of me asked me to replace the wiring of the system etc. The motor drives a large pump. The time relay is bad. The system was not used for a long period. No we don't have that much experience in industrial control. That's why i thought that time relays exist with test a option just like a normal contactor. I am a mechanical engineer and very interested in industrial control, so i will be asking a lot of questions on this forum. I want to know more about PLC's etc.

 

Then in this instance you likely want a DOM (Delay On Make) timer. I like Macromatic or Omron but any of a dozen will do. Manufacturer will likely depend on location. The circuit design is fairly common using contactors rated for your pump motor current. Anyway, you want a "Delay On Make" timer. You can place pilot lamps across your two contactor coils with the later labeled RUN. The first could be labeled START.

Ron

 

Or ON-Delay as opposed to On-Delay trigger.
Shown here.
Also NEMA-IEC symbol equivalent.
Max.

 

Good stuff!

Ron

 

Ron: Your full of surprises (i.e. secrets) with the OMRON relays. Cool stuff. I used idec with indiators and manual activation and what I really liked is the diagram on the top.

 

Then in this instance you likely want a DOM (Delay On Make) timer. I like Macromatic or Omron but any of a dozen will do. Manufacturer will likely depend on location. The circuit design is fairly common using contactors rated for your pump motor current. Anyway, you want a "Delay On Make" timer. You can place pilot lamps across your two contactor coils with the later labeled RUN. The first could be labeled START.

Ron

Hi Ron, we are leaning towards the Macromatic on-delay relays.

Question: What is the best time to set on the on-delay relay to drive a motor from star to delta?? Is there already a thread about this matter.

 

Hi Ron, we are leaning towards the Macromatic on-delay relays.

Question: What is the best time to set on the on-delay relay to drive a motor from star to delta?? Is there already a thread about this matter.

I used Macromatic and NCC (National Controls Corporation) quite a bit simply because sticking with a few manufacturers made for easy stocking of parts. Been awhile but as I recall your delay will depend on the motor HP (Horse Power). Since my plant was all 480 V Delta I never had to do the WYE Delta start. Anyway, the Macromatic are a fine choice.

Ron

 

Question: What is the best time to set on the on-delay relay to drive a motor from star to delta??.

It depends on whether there is a load present at start and motor size etc, a typical time would be in the order of ~5 secs from Star to Delta.
The time taken for the motor to reach full RPM in Star.
Max.

 

I used Macromatic and NCC (National Controls Corporation) quite a bit simply because sticking with a few manufacturers made for easy stocking of parts. Been awhile but as I recall your delay will depend on the motor HP (Horse Power). Since my plant was all 480 V Delta I never had to do the WYE Delta start. Anyway, the Macromatic are a fine choice.

Ron

Thank you

 

It depends on whether there is a load present at start and motor size etc, a typical time would be in the order of ~5 secs from Star to Delta.
The time taken for the motor to reach full RPM in Star.
Max.

Thanks Max

 

Incidentally what is the H.P. of the motor, and application?
We have 600v 3ph in Canada and we normally implement this on really large motors.
Max.

 

Incidentally what is the H.P. of the motor, and application?
We have 600v 3ph in Canada and we normally implement this on really large motors.
Max.

Yes, the motor is huge.

The motor is 55kW 3phase
U = 380-480/660-830 Volt. Motor runs on 440 volt. First star then delta.
I = 95A
n =1782 revs/min

The motor drives a large hydraulic pump.


Question: If a PLC sends an output voltage to an actuator and that actuator doesn't respond (send a feedback signal to the input of the PLC), does the
output of the PLC to the actuator stays energized??.

 

Question: If a PLC sends an output voltage to an actuator and that actuator doesn't send a feedback signal to the input of the PLC, does the
output stays energized??.

Normally the actuator would send a signal (feedback) to the PLC so the PLC knows where the actuator is with respect to its stroke and travel. So I am not quite sure I understand the question. The signal to the actuator would also be a function of how the PLC code was written. The PLC tells the actuator to do something, for example extend. The PLC then needs a way to decide if the actuator did in fact extend. The feedback could be a simple as a limit switch (yes or no) or a more complex LVDT (Linear Voltage Displacement Transducer) signal as a voltage proportional to the actuator's actual travel.

Ron

 

Incidentally if the Star Delta is part of the PLC system you can do the starter and timer sequence via the PLC without the need for the hard wired circuit you posted.
Apart from the two contactors of course.
Any PLC sequence can be programmed as you wish to achieve the desired result, but as Ron said, the PLC would need confirmation somehow in order to make a decision whether to terminate a sequence or not.
What is the make of PLC?
Max.

 

Normally the actuator would send a signal (feedback) to the PLC so the PLC knows where the actuator is with respect to its stroke and travel. So I am not quite sure I understand the question. The signal to the actuator would also be a function of how the PLC code was written. The PLC tells the actuator to do something, for example extend. The PLC then needs a way to decide if the actuator did in fact extend. The feedback could be a simple as a limit switch (yes or no) or a more complex LVDT (Linear Voltage Displacement Transducer) signal as a voltage proportional to the actuator's actual travel.

Ron

You did understand the question Ron. So if the output voltage from PLC to the actuator is 230V and as long as the PLC doesn't receive feedback from the actuator (limit switch), the output voltage from PLC to actuator stays 230 volts. Am i correct?

 

Incidentally if the Star Delta is part of the PLC system you can do the starter and timer sequence via the PLC without the need for the hard wired circuit you posted.
Apart from the two contactors of course.
Any PLC sequence can be programmed as you wish to achieve the desired result, but as Ron said, the PLC would need confirmation somehow in order to make a decision whether to terminate a sequence or not.
What is the make of PLC?
Max.

Hi Max, yes i know the manual start/stop can be done with a PLC. My question has nothing to do with the circuit i posted and the motor. It is a question in general about troubleshooting a fully automated process (Siemens S7-300). I want to know if the output of a PLC to a component stays energized, as long as the PLC doesn't receive a feedback signal from that component.

If it is true that the output stays energized as long as the the PLC doesn't receive a feedback signal (in case the component is not working), i can check with a voltmeter and know whether the PLC output or the component has failed.

 

The output stays on as long as the rung for the output coil stays high.
The output can remain on as long as the rung is made, feedback or not.
IOW it all depends on the Boolean functions of the rung that the output is on, do you have access to the PLC ladder? or at least a print out.
This is the beauty of having access to the monitoring S/W as the complete rung can be displayed and the status of each function can be seen as to whether it is on or off.
Max.

 

Comes down to what Max covered. You have a PLC making decisions with ladder logic and thus the "rungs" like rungs in a ladder. The PLC will make decisions on what it sees and how it is programmed to respond.

Ron

 

The output stays on as long as the rung for the output coil stays high.
The output can remain on as long as the rung is made, feedback or not.
IOW it all depends on the Boolean functions of the rung that the output is on, do you have access to the PLC ladder? or at least a print out.
This is the beauty of having access to the monitoring S/W as the complete rung can be displayed and the status of each function can be seen as to whether it is on or off.
Max.

Ok. now i understand. The status of the output depends on how the output is programmed. No i don't have access to the PLC ladder. I've made an appointment with a friend. He is an electronic engineer and electronic lab supervisor at the university. They have a Siemens S7-300 PLC in their lab. Tuesday, he will show me how the PLC works. I think i will spend a lot of days (time) in that lab doing research because i'm beginning to really like this stuff. I'm a mechanical engineer and i can combine my knowledge with PLC's, electric motors etc. I'll get back to you on Tuesday if i have more questions. Many thanks

 

I believe you will find the time spent with your friend interesting and enlightening. During my career I was fortunate in that I had the opportunity to work with several really great ME types. Frequently projects required extensive collaboration for developing test jigs and fixtures. Many a meeting and conversation often proved humorous as I applied my weak mechanical skills trying to explain what I wanted and the same was true across the aisle. We each needed to learn the other's side of the fence. Well enough to converse anyway.

Ron