Watlow Series 935A - Manual (Page 33)

Watlow Series 935A User’s Manual 3 1
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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