Despatch LBB2-xxA/B-1 - Manual (Page 24)

T HEORY OF O PERATION
LBB Series Oven Owner’s Manual
24 Version 15
Copyright © 2012 by Despatch Industries.
All rights reserved. No part of the contents of this manual may be reproduced, copied or transmitted in any form or by any
means including graphic, electronic, or mechanical methods or photocopying, recording, or information storage and
retrieval systems without the written permission of Despatch Industries, unless for purchaser's personal use.
3.3.1. High Limit Instrument
The LBB Series oven is equipped with a High
Limit instrument (Figure 6). The High Limit
instrument protects the oven or product by
discontinuing the heating process when the High
Limit is exceeded.
Set the High Limit instrument to a temperature
10°C - 14°C higher than the control instrument
setpoint, or to a temperature that should not be
exceeded in the process. If the setting on the High
Limit instrument is exceeded the heater shuts
down. See Table 3 for explanation about the High
Limit instrument.
Table 3. High Limit Instrument Explanations.
3.3.1.1. Product High Limit Instrument
If the product being processed has a critical high temperature limit, use the High Limit instrument
as a product High Limit instrument. Set the High Limit instrument to a temperature somewhat
below the temperature at which the product could be damaged.
3.3.1.2. Oven High Limit Instrument
If the product being processed does not have a critical high temperature limit, use the High Limit
as an oven High Limit instrument to protect the oven equipment. Set the High Limit to 204°C.

Reset the High Limit instrument by pressing the RESET
button on the instrument.
Features Description
OP1 Output 1 status value. (OP2 normally not used for LBB Ovens).
 C/  F Degree indicator.: Celsius or Fahrenheit
PV Process value
HSP1 High Limit setpoint 1. (LSP1 typically not used for LBB Ovens).
SP2 Setpoint 2 for output 2 (typically not used for LBB Ovens)
LOCK Lock status indicator
Scroll Key, used for advancing available displays
Increases a setpoint or mode parameter
Decreases a setpoint or mode parameter
Reset the High Limit, return to normal display
Figure 6. High Limit Instrument.