Watlow PM PLUS 6, Руководство пользователя

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Watlow PM PLUS™ 6 • 88 • Chapter 8: Features
Control Methods
Output Configuration
Each controller output can be configured as a heat output, a cool output, an alarm output or deactivated. No
dependency limitations have been placed on the available combinations. The outputs can be configured in
any combination. For instance, all three could be set to cool.
Heat and cool outputs use the set point and Operations parameters to determine the output value. All heat
and cool outputs use the same set point value. Heat and cool each have their own set of control parameters.
All heat outputs use the same set of heat control parameters and all cool outputs use the same set of cool
output parameters.
Each alarm output has its own set of configuration parameters and set points, allowing independent opera-
tion.
Auto (closed loop) and Manual (open loop) Control
The controller has three modes of operation: auto, manual, and off.
Auto mode allows the controller to decide whether to perform closed-loop control or to follow the settings
of Input Error Failure. The manual mode only allows open-loop control. The PM PLUS™ is normally used in
the auto mode. The manual mode is usually only used for specialty applications or for troubleshooting.
Manual mode is open-loop control that allows the user to directly set the power level to the controller’s out-
put load. No adjustments of the output power level occur based on temperature or set point in this mode.
Off deactivates the control loop and all outputs attached to the control loop are turned off.
In auto mode, the controller monitors the input to determine if closed-loop control is possible. The
controller checks to make certain a functioning sensor is providing a valid input signal. If a valid input signal
is present, the controller will perform closed-loop control. Closed-loop control uses a process sensor to
determine the difference between the process value and the set point. Then the controller applies power to a
control output load to reduce that difference. If a valid input signal is not present, the controller will indicate
an input error message on the Home Screen and respond to the failure according to the setting of Input
Error Failure. You can configure the controller to perform a bumpless transfer, switch power to output a
preset fixed level, or turn the output power off.
Selecting Auto or Manual Control Mode:
1. Go to
Operations — Setup — Control Loop —
2. Scroll to and select
Control Mode
3. Select the desired mode:
Auto or Manual or Off
This change takes effect immediately.
Bumpless Transfer
Bumpless transfer allows the controller to transfer to manual mode using the last power value calculated
in auto mode if the process had stabilized at a ±5 percent output power level for the time interval or 10
seconds, (whichever is longer) prior to sensor failure, and that power level is less than 75 percent. Reverse
Bumpless functionality will take effect when the control is changed from Manual to Auto mode. The con-
trol will preload the Manual Power value into the Integral and Proportional Terms, which will allow for a
bumpless transition. The normal PID action will then take over to control the output to the Set Point value.