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DCP200 Profile Controller & Recorder - Product Manual
Page 164 Glossary 51-52-25-150, Issue 1 – April 2009
Triac
A small internal solid state relay, which can be used in place of a mechanical relay in
applications switching low power AC, up to 1 amp. Like a relay, the output is time
proportioned, but much faster switching cycle times are also possible, leading to superior
control. As a solid-state device, a Triac does not suffer from contact degradation when
switching electrical currents. A snubber should be fitted across inductive loads to ensure
reliable switch off the Triac. A triac cannot be used to switch DC power.
Also refer to: Cycle Time, Relay, SSR and Time Proportioning Control.
USB Menu
If the USB option is fitted, the USB Menu can be accessed from the Main Menu. This menu
is lock code protected.
The USB Menu allows the user to read or write files to a USB memory stick. The current
configuration of the instrument can be downloaded to the stick or the instrument can be
completely reconfigured using a pre-stored file that has been downloaded earlier, created
using the PC software, or even taken from another instrument.
If the Data Recorder option is present, the recordings can be downloaded to the stick for
transport to the users PC for analysis. If the Profiler option is present, profiles can be
downloaded to the stick or upload to the instrument using a pre-stored file that was
downloaded earlier, created using the PC software, or even taken from another instrument.
Refer to the USB Menu information in the Configuration & Use section.
Also refer to: Data Recorder, Lock Codes, Main Menu and Profiler
Valve Motor Drive Control (VMD)
This instrument can only control modulating valves that have a valve positioning circuitry that
adjusts the valve position according to the level a DC linear mA or voltage output signal.
Such valves normally require PI control instead of full PID.
Motorised modulating valves that do not have this type of circuit require special Valve Motor
Drive controllers which have a “Three Point Stepping” control algorithm.
Solenoid valves can also be controlled using the standard PID algorithm as they behave in a
similar way to relays, having just two states, open or closed.
Also refer to: Control Deviation, Linear Output, Modulating Valve, PI Control, PID, Relay,
Solenoid Valve, and Three Point Stepping Control.
VDC
This stands for Volts DC. It is used in reference to the linear DC Voltage input ranges.
Typically, these will be 0 to 5V, 1 to 5V, 0 to 10V or 2 to 10VDC. Linear outputs can also
provide DC voltages.
Also refer to: Auxiliary Input, Input Range, Linear Input, Linear Output, mADC and mVDC..
VMD
- Refer to Valve Motor Control.