Watlow Series 935A User’s Manual
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Convection Oven Application
Scenario
A master chef bakes bread at 350°F for 30 minutes. He wants the oven at the proper temperature with an indication when it is ready to
begin baking. He isn't concerned if the oven is 10° cool at first. After he loads the oven, the chef wants to start the countdown time by
pressing a key. When the baking time is complete, he wants a 10 second audible indication that the bread is done.
Recommended Control
A Series 935A-1CD0-000G control.
•
Switched dc Output 1 wired to a dc input solid state relay (SSR) switches the heaters.
•
Electromechanical relay Output 2 wired to an AC audible indicator provides “done” indication.
Configuration Menu Set-up
[`C_F]
=
[``°f]
°F
[dIsp]
=
[Acti]
After a
ß
press, actual temperature appears for 15 seconds.
[`Ot1]
=
[hEAt]
Heating output
[`Ot2]
=
[tMS]
Time; minutes:seconds
[tIM]
=
[SGon]
Output 2 turns ON briefly at the end of the timing cycle.
[Strt]
=
[rdYA]
Timer waits to countdown until temperature deviation from set point <
[`rdy]
value and the
ß
key
is pressed.
[`rdY]
=
[``10]
Ready band; 10°F
[``St]
=
[``10]
Output 2 turns ON for 10 sec. at the end of the timing cycle.
Operations Menu Set-up
[tMr]
=
[3000]
Bake time; 30 minutes
[IdLE]
=
[``75]
The set point temperature before a timing cycle starts and after a timing cycle completes.
Set Point =
[`350
°F
Operator/Control Actions
•
With the oven "idling" at 75°F, the chef starts the preheat cycle with a
,
press. The display immediately shows 30:00 with the
colon ON steadily. The RDY LED is off. Series 935A begins to control to the 350°F bake set point.
•
As the actual oven temperature increases to within the Ready Band at 350°F ±10°F, the RDY LED turns on. The chef loads the
oven and presses ß to acknowledge the Ready Band and thereby start the bake cycle.
•
Time starts counting down. Actual temperature displays for 15 seconds after the
ß
key is press. Then time displays with the
colon flashing.
•
If temperature deviates out of the Ready Band (less than 340°F or more than 360°F), timer countdown will pause, but will con-
tinue as soon as temperature re-enters the ready band.
•
When time reaches 00:00, Output 2 turns on for 10 seconds sounding the audible indicator. The chef can stop the audible indica-
tor by pressing
.
. The Series 935A then automatically shifts to the 75°F idle set point.
Timer Example
