UVM-1000
LIT-12013155
24
User Config Settings
The
cfm/Press at 10 V
field (see
Figure 5
) sets the control signal
and feedback signal scaling into and out of the UVM. If the UVM
is configured to operate with a Venturi valve (most cases) then
this value represents what cfm the 10V input and output signals
represent.
For example, if a value of 1500 is entered, then a 10 V signal
applied to the IN connection specifies a cfm of 1500 cfm is
requested, and a 10 V signal from the Vo connection indicates
the valve is providing 1500 cfm. This value is set initially by the
factory and is matched to the size of the valve attached to the
UVM. Typical values are:
8 in. = 800
10 in. = 1100
12 in. = 1600
14 in. = 2300
The
FB Input Filter Factor
is a filtering or dampening factor
applied to the raw feedback signal from the position feedback
sensor on the valve. The typical value is 3.
The SP Input Filter Factor is a filtering or dampening factor
applied to the raw control signal applied to the IN connection
of the UVM. It has been found that some third party controllers
use a PWM method to produce their AO signals. This typically
results in a signal that varies by up to 0.5 V at 10 Khz. The UVM
is sensitive to this and results in the actuator jittering between
various positions as it follows the (moving) input control signal.
This value is typically 10-20, but can be higher (50 or more) for
third party controllers with unsteady AO signals. Note that the
higher this value, the less responsive the UVM is to sudden
changes in the control signal.
The
Gain PressSen
and
Offset PressSen
fields are used to
scale an optional external pressure sensor so that the sensors
output voltage range converts to the appropriate pressure range
on the UVM. The use of a pressure sensor as a DP monitor is
only active when the
Use Press Sens as DP
selection is active
or checked. The pressure sensor can be used to monitor the
DP pressure across the valve and give a 0 cfm output voltage if
the pressure falls below the value set in the
No Flow Press
field
(typically 0.6 in. W.G.).
When using an analog pressure sensor with a voltage output
connected to the Sens_In pin (see
UVM Installation Manual
), the
following scaling should be used:
The scaling is derived from : 0 V = 0 counts, 5 V = 4095 counts
= x Press = (x – Offset) * Gain
Gain = ( ( Ph – Pl ) / ( Vh – Vl ) ) * ( 5 / 4095 )
Offset = ( 4095 / 5 ) * ( Vh – ( Ph * ( ( Vh – Vl ) / ( Ph – Pl ) ) )
Where Vh is the sensor voltage at the high pressure Ph, and Vl
is the low voltage at the low pressure Pl.
Clicking the
Calc
button (see
Figure 5
) allows this calculation to
be done automatically.
This brings up a calculation dialog (see
Figure 6
) where the
sensor pressure range and output voltages can be entered. The
Compute
button calculates the
Gain
and
Offset
and enters these
values in the
Gain PressSens
and
Offset PressSens
boxes. If
these values are correct, click the
Set PressSens Gain
and
Set
PressSens Offset
button to send the values to the controller.
The pressure, in in. W.G. below, which the flow in the valve is
deemed to be invalid, and should produce a 0 cfm flow feedback
signal, is entered in the
No Flow Press field
(see
Figure 5
). For
Triatek standard flow valves, this value should be 0.6 in. W.G.
The
Flow Sw Delay
setting (see
Figure 5
) is used in instances
when a DP switch is used with the valve to detect when there is
insufficient DP across the valve to produce a reliable cfm. The
delay value is in seconds and is the time between when the DP
switch detects a low flow and when the UVM zeros out the cfm
feedback signal. This value is only relevant when the
Use DI
as
DP
or
Use Press Sens
as
DP
selection is active or checked.
The
Flt Stroke Time
(see
Figure 5
) is for instances when a
“floating” (drive up, drive down) actuator is used with the UVM.
The actuator counter clockwise (CCW) and clockwise (CW)
inputs are connected to the CCW and CW outputs of the UVM.
The actuator common and the UVM COM are connected to the
“active” and “neutral” respectively of a 24 VAC supply. The
Float
DO
is
DP Out
selection should be un-selected. The
Fit Stroke
Time
is the stroke time of the floating actuator, typically 60 or 90
seconds. It should be noted that floating actuators are not very
accurate for using a stroke time to determine position, and as
such actual requested cfm and achieved cfm may not match.
The floating actuator can also be used with the feedback sensor,
where the valve position is determined entirely by the feedback
value and not the stroke time of the actuator. To enable this
mode of operation, check the FB (
not Time
)
Float Act
selection.
The
Float Dead Band
(see Figure 5) is the dead band associated
with the floating actuator positioning. This value is requested cfm
change before the actuator moves to new position.
When the UVM is used with a VAV box, the K factor for the box
and the area of the VAV Box are set in the
VAV Box K Factor
(see
Figure 5) and
VAV Box Area
fields. The use of a UVM with a VAV
box is enabled by setting the
Unit
is
VAV Box
check box. The
pressure sensor input on the UVM is used to provide the flow
pressure from the VAV box flow probe. Again, the
Gain PressSen
and Offset PressSen fields need to be set to calibrate the used
pressure sensor.
Figure 6. Press Sens Calc dialogue box