Perhaps the last mail did not go out.
Regards,
Ramon
> -----Original Message-----
> From: Dehoyos, Ramon
> Sent: Wednesday, August 06, 2003 1:49 PM
> To: [log in to unmask]
> Subject: RE: [TN] Temp stability in Zone 3
>
> Ed:
> Change the Zone 4 and 5 temp to 140 and see if the problem still
> persists. That would eliminate the exhaust situation.
> Regards,
> Ramon
>
> -----Original Message-----
> From: Hal Winslow [SMTP:[log in to unmask]]
> Sent: Wednesday, August 06, 2003 10:42 AM
> To: [log in to unmask]
> Subject: Re: [TN] Temp stability in Zone 3
>
> Ed,
> As you allude to, the exhaust may play a factor here. I would spend some
> time making sure that all the "higher temp" zones are clean. If, for the
> sake of argument, the exhaust flow was reduced on either Zone 4 or 5, you
> might see some of the air, and thus the "energy" flow from zone 4 out
> through the zone 3 exhaust, thus raising the temperature.
>
> Good luck,
> Hal
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Ed
> Popielarski
> Sent: Wednesday, August 06, 2003 10:28 AM
> To: [log in to unmask]
> Subject: [TN] Temp stability in Zone 3
>
>
> Hi everyone,
>
> I ran into an issue that has me scratching my head (no, it's not
> fleas!) My customer is having temp stability problems in Zone 3 of a BTU
> VIP70 reflow oven no gas. Below are the setpoints of each zone in deg C:
>
> Z1T: 140
> Z1B: 140
> Z2T: 140
> Z2B: 140
> Z3T: 140
> Z3B: 140
> Z4T: 180
> Z4B: 180
> Z5T: 230
> Z5B: 230
>
> All zones are holding +/- 1 deg C EXCEPT Z3T which after setpoint is
> reached, climbs very slowly (about 5 deg C/hour) and Z3B at half that
> rate. Once this 5 deg deviation is reached, the system alarms (as it
> should). I have confirmed the solid state relays are not "leaking"
> (swapped them with good zone), the computer is setting the duty cycle of
> these at 0% (once setpoint has been reached) , this has been confirmed
> electrically, and there are no ground faults in the heaters, convection
> fans are running. BTU has offered the customer little, if any advice.
>
> My theory is that "stray energy" from Z4 and possibly Z5 are heating
> Z3 which, possibly due to inadequate ventilation, cannot cool. I was
> hoping someone in the forum might have experienced a similar issue and
> would share that experience. I haven't measured the exhaust flow rate yet,
> as I didn't want to chase a "ghost", but it IS running.
>
> It's not often I get stumped (Steve G. can attest to that!) but this
> one really has me baffled.
>
> Regards,
>
> Ed Popielarski
> QTA Machine
> 27291 Jardines
> Mission Viejo, Ca. 92692
>
> Phone:949-581-6601
> Fax: 949-581-2448
> Cel: 949-337-2578
>
> WWW.QTA.NET <http://www.QTA.NET>
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