MicroTrans
II
Summing Operation & Maintenance Manual
Paragon Controls Incorporated
1
Revision Level 002
1. INTRODUCTION
1.1. DESCRIPTION
The MicroTrans
II
Summing Signal Processor employs current state-of-the-art digital microprocessor
technology to produce highly stable and accurate air flow measurements. The MicroTrans
II
is factory
configured and calibrated to the exact specification determined at time of order. The MicroTrans
II
Summing Signal Processor is capable of receiving an external air flow signal (4-20mA / 0-10 VDC) ,
summing the two air flow values and displaying the MicroTrans
II
measured air flow and the total air
flow. The Microtrans
II
offers an optional controller that utilizes a proprietary algorithm which results in
true three mode control incorporating proportional band, integral (reset) and inverse derivative (P, I,
1/D) controller functionality and tuning. The controller will provide responsive modulation of a control
damper or variable speed drive guaranteeing a constant airflow or pressure is maintained. Additional
optional features include AutoZero; High/Low Remote Alarms; Temperature Compensation; and
LonWorks®, BACnet®-MS/TP Master, and Modbus® Slave communication. Simple field
configuration of engineering units, operating range, process noise filtering, alarm set points, etc., are
performed via password protected intuitive menus that are accessed through the integral six button touch
pad. Device monitoring and configuration can also be performed by a building management system
through a LonWorks®, BACnet®-MS/TP Master, or Modbus® Slave communication network.
1.2. BASIC
OPERATION
The transducer receives a differential pressure signal from the pressure or flow sensing element. This
signal is scaled and linearized before being displayed along with the total air flow value from an external
transmitter. The process output (4-20mA, 0-5VDC, or 0-10VDC) signal is selectable between the
Microtrans
II
measured air flow and the total air flow value. The AutoZero option detects and corrects
any zero offset caused by large ambient temperature changes. The Temperature Compensation option
compensates the flow and velocity signal for density changes caused by variations in the process air
temperature; an external temperature transmitter or input signal from the building management system is
required.
1.3.
PI1/D CONTROL LOOP
The PI1/D controller measures the difference between the process value and the setpoint value to
determine the error value. The controller continually attempts to remove this error by varying the
control output signal to adjust the variable frequency drive (VFD) or damper. To optimize the control
loop response, the control parameters (Proportional Band [PB], Integrator Time [Reset], and Inverse
Derivative [1/D]) may need to be adjusted.
1.3.1. PI1/D Parameter Description and Response
-
Proportional Band (PB):
The function of the PB parameter is to amplify the current
error value (process value minus setpoint value) to make a quick control change to a large
error change. The PB adjustment range is 1 to 100%. The formula is Gain = 100% / PB.
For example, a PB setting of 100% is a gain of 1; i.e., it takes a 100% error signal to get a
full response of the controller. Conversely, a PB setting of 10% is a gain of 10; i.e., it
takes a 10% change of the error signal to get a full response of the controller. Therefore,
decreasing the PB value will cause the controller’s response to speed up.
-
Integrator Time (Reset):
The function
of the
Reset is to remove any residual error
present after the PB and 1/D functions. The Reset adjustment range is 1 to 300 seconds.
Decreasing the Reset value will cause the controller’s response to speed up.
