ASCO Series 300 ATS No Transfer

[onsitepower]

Hey guys, hopefully someone can help me with this issue. I have an ASCO series 300 ATS 3 phase 120/208 400 Amps. When utility power fails it sends the signal to start the generator as it should, but it does not transfers to emergency. I have check voltage line to line and to neutral and hertz and everything seems correct. Even the emergency power available light at the membrane is lit. I manually transfer to emergency and when utility returns it will retransfer and shut down the unit properly. I removed the control board and installed on another ATS same voltage and amps, and it works perfectly. Just in case I also replaced the rectifier bridge with no results. The coil seems to be working since it retransfers. I have talk to ASCO but they pretty much want to send a tech to verify the unit. What am I missing?? I will appreciate any advise.

Kind regards

 

[collies99]

Are all the fuses ok

 

[collies99]

Did a quick read on your manual, time delay could be set as high as 5 minutes. There is a delay bypass button if you want to force transfer to emergency, did you try pressing the button ? P2 is the timer potentiometer setting.

 

[onsitepower]

I have check all the potentiometers and verified the dip switches, delay bypass won't work except from emergency to normal. Have not seen any fuses. Where are they located?

 

[collies99]

Reread the manual, aslo included in link. Sorry no fuse !

P2 is the transfer to emergency timer and P1 is the retransfer to normal timer. Wipe P2 potentieter back can forth, perhaps it is not making good contact.

Check the sensor setting, page 4-1.

Trouble shooting checks, Table 3-1.

Good luck

 

[waross]

Check the "Inhibit Transfer to Emergency" Dip switch.
Check the frequency set-up. 50hz or 60 Hz.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[wayne440]

My guess is a defective or out of adjustment microswitch, or a wire pulled off of same.

 

[unclebob]

Seams like voltage or frequency differential is too high.

 

[onsitepower]

I removed the control board and install it on another ATS same voltage and amps rating and it work flawlessly, it seems the dip switch settings are correct ( I have also verified them 3 times ) Voltage and frequency from the emergency side are 120 line to neutral and 209 phase to phase. Hertz 60.9. LED emergency source accepted in on. It just won't transfer.

 

[wayne440]

The operators manual is not going to be much help in this situation. The actual schematic may be far more helpful if you can lay hands on it. Once you do so, you will see that if you eliminate the control board and rectifier/actuator as suspects, there are few components left. Two of them are microswitches mounted on and activated by the switch mechanism. I have not called on ASCO recently, but a couple of years ago, an electronic copy of the schematic could be had for the cost of asking for same and having the model and serial number of your switch on hand.

 

[collies99]

Last place to look would be bad connections between the circuit board to outgoing connector(s) a bad solder joint, poor board to connector connection, broken wire in the harness of the connector or any outgoing wire from the board.

In your original question you indicated you did as such took the board and place it in another unit at it worked. Have you tried taking the other unit's board and tried in on the original Asco switch ? We would be looking results that it "did NOT work", so that it would indicate something in the Switch and not the board, and 2 workings boards did not made the switch transfer. Now we just trouble shoot all else external to the baord.

 

[trosepe]

The 300 series has an in-phase monitor that can be enabled or disabled. The ASCO ATS transfers in 150 ms with no neutral position so they come standard with an in-phase monitor to prevent nuisance tripping. The in-phase monitor needs to see two phaser crossing to establish the transition speed. If the two sources are very close to the same frequency the Phaedra will circle one another and you won't get the two crossings. You can try disabling the in-phase monitor or slightly adjust the generator frequency up or down.

 

[waross]

The phase monitor is only active on re-transfer to normal power. When the mains fail, there is nothing to compare the emergency source with and so the in phase monitor is not active.
This leads to another suggestion; Are the line and emergency leads switched?? Probably not or you wouldn't get a generator start signal.
Take a close look at the micro switches that Wayne440 mentions.

Bill
--------------------
"Why not the best?"
Jimmy Carter