Hmi soft start button not working

syed misbah

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• Jun 27, 2012

• #1

Hi everyone here, I'm facing problem with one of our machine.,which have got Hmi .this Hmi has several soft start and stop buttons,which turns on/off relay,which in turn controls the drive. THE START buttons normally when are on will highlight the word start on the button itself .Now, the problem is with one start button which highlights the green color nly and doesn't start one of the motors. The motor control works manually. I was wondering the problem to be with hmi, or could be with plc. Please provide some inputs that can help me solve the issue

 

moggie

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• Jun 27, 2012

• #2

Go online to the PLC and monitor the program to see if the HMI "Soft button" changes state within the program, or if there is something else that is stopping the output for the motor relay?

 

syed misbah

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• Jun 27, 2012

• #3

Thanks for quick reply, there is one error on hmi screen 'thermal overload '.

 

moggie

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• Jun 27, 2012

• #4

syed misbah said:

Thanks for quick reply, there is one error on hmi screen 'thermal overload '.

Click to expand...

Is this for your motor (motor has overloaded/tripped?)
Reset the error!

 

syed misbah

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• Jun 27, 2012

• #5

It's for that motor, but there is no overload problem with motor. It runs ok manually.

 

moggie

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• Jun 27, 2012

• #6

syed misbah said:

It's for that motor, but there is no overload problem with motor. It runs ok manually.

Click to expand...

Then do you not think that this could be the problem with your motor?

How do you run it manually?

Check the PLC Program to see what gives you this error message.

Then You will need to check the electrical schematics to see what the PLC input is and make sure it is correct.

 

Last edited: Jun 27, 2012

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• Jun 27, 2012

• #7

From your description I would check the input to the PLC that has the motor overload on it. If the overload is not really tripped your PLC seems to think it is.

 

rguimond

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• Jun 27, 2012

• #8

syed misbah said:

It's for that motor, but there is no overload problem with motor. It runs ok manually.

Click to expand...

It's doubtful that there are seperate overload contacts for the PLC and manual starter. My guess is that the coil for the motor starter has parallel sources (PLC and Manual START button) and that the overload is only in series with the PLC output.

 

Ned_Flanders

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• Jun 27, 2012

• #9

rguimond said:

It's doubtful that there are seperate overload contacts for the PLC and manual starter. My guess is that the coil for the motor starter has parallel sources (PLC and Manual START button) and that the overload is only in series with the PLC output.

Click to expand...

Most overloads I work with have a normally closed contact for the starter coil and a normally open contact to indicate an overload to the plc. The drive is probably stopped in the software somewhere.

I worry a little as I believe the fault has been diagnosed...but the op thinks it must be something else....

 

syed misbah

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• Jun 28, 2012

• #10

Hi guys, thanks for giving feedback, The motor is working fine manually. The speed control, I have set it to manual mode in the vfd,otherwise the plc speed. And the vfd connection is direct now. Well.,, I can't find way to reset the error 'thermal overload '.

Also ,please note that in the plc, the input that is coming from soft start button is off, hence the output of the plc that turns on the vfd is off.

 

uptown47

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• Jun 28, 2012

• #11

Is this a new system or a system that has previously been working (i.e. is this Thermal Overload error correct or just a contact in the software the wrong way around?).

It sounds like the Thermal Overload error is preventing the PLC from turning on the motor. You need to go online (or get some drawings) and establish where the Thermal Overload signal is coming into the PLC and then find out why it's on.

Also, what's generating the error? Is it coming from the inverter? Are there any warning/errors on the inverter?

It could be that your software is wrong (if it's new software) or that the signal is the wrong way around (i.e. someone has changed some contacts and swapped NC for NO etc...)..

 

alielectrical

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• Jun 28, 2012

• #12

Misbah,

Pls inform what HMI program you are using as well as the type of plc and hmi.
Is it possible to monitor the program?

 

gscure

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• Jun 28, 2012

• #13

Vfd

I would look at the VFD as the culprit. It might be sending the thermal overload signal back to the PLC. The reason it works in manual could be because it is designed to be energized through a bypass contactor. The VFD has to be reset in order to clear the error and return the system to automatic.