Theory of operation – Despatch Protocol Plus Controller (Heat Only) User Manual

Page 12

HEORY OF

PERATION

Protocol Plus Owner’s Manual

Version 2

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Theory of Operation

The Protocol Plus is a modular microprocessor based digital temperature controller
(Figure 1). The Protocol Plus controller operates as a dual-
functioning controller/high limit instrument. The control
portion utilizes a time-proportioning voltage signal to
control heating devices with minimal temperature
fluctuations.

The high limit portion protects the product and/or the oven
from overheating. If the product being processed has a
critical high temperature limit, the high limit setpoint
should be set to a temperature somewhat below the
temperature at which the product could be damaged. If the product does not have a
critical high temperature limit, the high limit setpoint should be set 5 to 15 degrees higher
than the maximum programmed setpoint at which the oven will operate.

The Protocol Plus controller provides three primary operating modes:

Manual

: Oven operates continuously at a fixed temperature until turned off.

Timer

: Oven operates at a fixed temperature for a user-selected time period, then

automatically turns off.

Profile

: Temperatures increase or decrease as defined by one of eight pre-

programmable ramp and soak profiles. Each profile contains up to eight ramp and
soak segments. The profiles can be linked to provide additional temperature
combinations.

In addition these primary operating modes, the Protocol Plus controller employs a
Stopped Mode, Auto Start Mode, Setup Mode and Fast Start Mode:

· Stopped Mode: All control and relay outputs are off. Stopped Mode is integrated

into each of the modes of operation.

· Auto Start Mode: Control may automatically start Manual, Timer, or Profile

mode based on a preset time and day. Optional event outputs can be utilized
during Manual, Timer, or Profile modes.

· Setup Mode: Provides access to control configuration and programming of

profiles. Setup Mode contains ten separate electronic “Pages” where configuration
and programming parameters (Menu items) are found and can be manipulated.

· Fast Start Mode: Provides for automatic startup of an operating mode when

power is applied. Use Fast Start Mode if the same mode of operation is used every
day. The user can turn on the power and the oven will start the desired process
automatically. The Fast Start Mode is controlled by the Power-Up Start
parameters on the Control page.

Figure 1. Operator Interface.