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Technical Service Manual 18 Revision Dat e: August 2004 B - HEA TING SYST EM In the following “Problem s and Pos sible Solutions”, the m os t lik ely cause is listed f irst...inves tigate the m ost lik ely first, then pr…

Technical Service Manual 17 Revision Date: August 2004

OVEN CELL ARRANGEMENT

The cells are mounted both above and below the conveyor, as shown, forming a series of “Heat Zones”.

Each Heat Zone circulates heat primarily within itself, thereby maximizing the thermal isolation between zones.

An insulated exhaust plenum mounted under the Bonnet collects gases from the individual upper heat cell exhausts and

conveys the combined flow to the Plant Exhaust System.

An oven contains several heating zones (5,7,8,10, or 12) and 2, 3, or 4 cooling zones. Cooling zones are identical to

heating zones except they have no heating elements and no exhausts (only gas intakes).

A properly operating oven is an inter-dependent system. When a heater or fan malfunctions, the balance and

performance of the oven as a system may be affected. Usually, an irregularity in operation could be the result of any one

(or more) malfunctions.

INSULATED CONTROLLED

EXHAUST PLENUM

TO PLANT

EXHAUST

SYSTEM

CELL 2BCELL 1B CELL 3B

CELL 4TCELL 3TCELL 2TCELL 1T

Zone 1

Technical Service Manual 18 Revision Date: August 2004

B - HEATING SYSTEM

In the following “Problems and Possible Solutions”, the most likely cause is listed first...investigate the most likely first,

then proceed to the next one in the list.

PROBLEMS AND POSSIBLE SOLUTIONS (The most likely cause is listed first)

HEATING PROBLEMS

OVER TEMPERATURE PROBLEM:

Not more than 10

C above set point and stable:

1. Temp drift from adjacent heater See: 1,2

2. Possible cell fan failure: See: 2, 3

Slow rise past set point:

1. Temp drift from adjacent heater See: 1, 2

2. Thermocouple problem in opposite heater See: 5

3. Radical recipe change See: 31

4. Short to ground in heater See: 8

Rapid rise past setpoint.

1. Latched control SSR See: 7, 12

2. Loose thermocouple wire See: 25

3. Controller Failure See: 11

4. Radical recipe change See: 31

5. DC stage of control SSR hot See: 4

Technical Service Manual 19 Revision Date: August 2004

UNDER TEMPERATURE PROBLEM.

CELL TEMPERATURE RISES, BUT DOES NOT REACH SET-POINT:

1. No power to heater:

2. Open circuit breaker See: 10

3. Control SSR failure See: 12

4. Loose wire See: 16

5. Open heater element See: 13

6. Shorted thermocouple See: 18

7. Excessive exhaust flow See: 14

8. Excessive air entering oven See: 15

9. Under voltage or Phase failure See: 19

Cell appears to stay cold:

1. Thermocouple short See: 18

2. Controller failure See: 11

3. General oven failure See: 20

Temperature drops down below set point:

1. Power loss to heater. See: 19,21

2. Control SSR failure See: 12

3. Thermocouple short See: 18

4. Controller failure. See: 11

5. Radical recipe change See: 31

RANDOM HIGH TEMPERATURES.

1. Thermocouple connection See: 25

2. Grounding. See: 28

3. Conveyor motor noise. See: 26

4. Failure of control SSR See: 12

5. AC Signal on T/C or T/C Wires See: 27

RANDOM LOW TEMPERATURES.

1. Failure of control See: 11

2. Erratic exhaust. See: 14