Relay Testing

[andywileman]

Hi,

What I am trying to do is test relays, using an automated test procedure.

The procedure takes the following steps:

1.       A NI9472  DO card and transistor drive turns the relay on/off via energising the coil (needs the time period to be variable).

2.       Counts how may cycles the relay contacts have operated, this will easily be in excess of 100,000 cycles.

3.       Every 100 cycles (again variable), the contacts are held closed, the load circuit (the current the relay is switching, which will be 15A at 30V) is disconnected, via another relay and a measurement is taken via a separate four wire method.  This consists of a 6V supply being placed across the contacts (switched in again via a relay) with a 1A current flowing through the contacts, the voltage drop across the contacts is then inputted into the NI AI NI9219 card (this is in the region of 10’s of mA) and is directly proportional to the contact resistance, which is what I want to measure.

4.       The measurement is taken and stored and the measurement circuit disengaged, the load circuit re-engaged, and another 100 cycles is counted before the process goes back to stage 3.

5.       This process goes on until the relay fails and hopefully a large set of contact resistance data is gathered.

I have no real experience with NI Labview.  

I have looked at the basic academic tutorials and have come up with the following programme for stage 1, however I can't get the DAQ Assistant to output every cycle

Would this be a very difficult programme to implement for the novice?  The academic tutorials seem straight forward but when I try to do someting it seems very difficult.

Hoping someone may be able to help, thanks

Andy

[crossrulz · Accepted solution]

There's nothing really difficult to this.  Just make sure your logic is correct for when you do the resistance checks.  This should get you most of the way there.

[andywileman]

Thanks for help, I don't think I would have come up with that myself from the basic tutorials.

[andywileman]

Hi,

Yesterday I very kindly had some help from crossrulz in setting out the following procedure.  Today, the National Instruments representative called and said I should implement my programme as a "State Machine", which I have attempted in the programme attached.  I was wondering how I might now implement the procedures 3 to 5 in this State Machine format as it seemed very complecated in the brief time we had. 

What I am trying to do is test relays, using an automated test procedure.

The procedure takes the following steps:

1.       A NI9472  DO card and transistor drive turns the relay on/off via energising the coil (needs the time period to be variable).

2.       Counts how may cycles the relay contacts have operated, this will easily be in excess of 100,000 cycles.

3.       Every 100 cycles (again variable), the contacts are held closed, the load circuit (the current the relay is switching, which will be 15A at 30V) is disconnected, via another relay and a measurement is taken via a separate four wire method.  This consists of a 6V supply being placed across the contacts (switched in again via a relay) with a 1A current flowing through the contacts, the voltage drop across the contacts is then inputted into the NI AI NI9219 card (this is in the region of 10’s of mA) and is directly proportional to the contact resistance, which is what I want to measure.

4.       The measurement is taken and stored and the measurement circuit disengaged, the load circuit re-engaged, and another 100 cycles is counted before the process goes back to stage 3.

5.       This process goes on until the relay fails and hopefully a large set of contact resistance data is gathered.

I have no real experience with NI Labview.  

I have looked at the basic academic tutorials and have come up with the following programme for stage 1, however I can't get the DAQ Assistant to output every cycle

Would this be a very difficult programme to implement for the novice?  The academic tutorials seem straight forward but when I try to do someting it seems very difficult.

Hoping someone may be able to help, thanks

Andy

[sohail11]

I think this explains better.

Image courtesy: Studentsheart.com