5
VOLTMETER APPLICATION
Indicating the Speed of a D.C. Motor
A foreman in a plant wants to get a more accurate indication of the speed
at which a variable speed DC motor drive is operating. The only indication
he has now is the position of a dial on the control panel.
The motor has a tachometer generator that will output a 10 VDC signal
when the motor is running at its maximum speed of 1800 RPM. The power
supply of the control has a 15 VDC output that can supply power to
the CUB4V.
Since this application requires a non-standard readout, it will be
necessary to scale the display. The Scale DIP switch is set to the “ON”
position to enable the Scale Potentiometer. The Division Factor is calculated
using the formula:
D.F.
=
(Maximum output) x D.D.P.
(Desired Display)
D.F.
=
10 x 1000
1800
D.F.
=
5.5
Since the division factor falls between 1.2 and 10.5, DIP switch position S2
is set to the “ON” position, according to the Division Factor Selection Chart.
To scale the CUB4 Voltmeter, the motor is run at full speed and a
calibrated photo tachometer is used to obtain the exact speed. The Scale
Potentiometer on the CUB4 Voltmeter is then adjusted until the display
reading agrees with the tachometer. Alternately, the output of a precision
voltage source set to +10 VDC can be connected to the signal input of the
unit and then adjust the scaling potentiometer for the desired reading.
ORDERING INFORMATION
TYPICAL VOLT & CURRENT MEASUREMENT APPLICATIONS
CURRENT METER APPLICATION
Analog Meter Replacement
A manufacturer wants to replace several 1 mA DC analog meter
movements with easy to read CUB4 Current Meters with backlighting. One
application involves measuring the flow rate of a liquid to indicate 0 to 250
gallons per minute.
Since 1 mA of current flow requires a display reading of 250, the CUB4
Current Meter will need to be scaled. The Scale DIP switch is set to the
“ON” position enabling the Scale Potentiometer. The proper current range
for the application is then selected. The Scale potentiometer will divide the
display reading by 1 to 13, for the particular current range selected. A
reading of 250 is 4 times less than the normal reading at 1 mA for the 0 to
1.999 mA range, therefore the jumper is installed in the 0-1.999 mA range
position. No decimal point is selected because the resolution is 1 gallon.
The CUB4 Current Meter can now be scaled. Apply 1 mA to the signal
input and adjust the scale potentiometer to the desired reading.
TROUBLESHOOTING
For further technical assistance, contact technical support at the appropriate
company numbers listed.
MODEL NO.
DESCRIPTION
PART NUMBERS
DC Voltmeter
CUB4V000
CUB4V
CUB4V010
CUB4V020
DC Current Meter
CUB4I000
CUB4I
CUB4I010
DC Current Meter W/Red Backlighting
CUB4I020
MLPS
Micro Line/Sensor Power Supply
MLPS1000
DC Voltmeter W/Red Backlighting
DC Voltmeter W/Yel-Grn Backlighting
DC Current Meter W/Yel-Grn Backlighting
