Liquid Controls SP720-2 User Manual
INSTALLATION & OPERATION
MANUAL
SP720-2
Loop Powered
2 Wire Modulated Carrier Ampl i fier
4-20mA Transmitter
DOC#: MN-720
Sponsler, Inc.
SP720-2 Transmitter
pg
2
DOC# MN-720
Temperature:
Input Voltage:
Minimum = 7V + (20mA X RL)
Signal Input:
Frequency 0-3500Hz with 50KHz Carrier
4mA @ 0Hz, 20mA @ desired full scale frequency
LED Signal Indicator
Enclosure:
FM Approved, CSA Certified
Weight 1.7 lbs.
Analog Output:
Features:
SPECIFICATIONS
Operating -40 to 85°C
Storage -65 to 125°C
Maximum = 28V + (4mA X RL)
Protected against polarity reversal
(Requires pickup coil 1-1.3mh)
Full scale range = 35Hz-3500Hz selectable
Response time = 95% of change in 1 second
Linearity = .3% F/S
Tempco = <2% of reading over entire temperature range
Mounts directly on flowmeter
Class I Groups B, C, D
Class II Groups E, F, G
The SP720-2 Loop Powered 2 Wire Modulated Carrier Amplifier 4-20mA Transmitter is a
unique meter mounted device designed to combine the advantages of the modulated carrier
principle with the convenience and accuracy of a loop powered 4-20mA transmitter. When
incorporated with a frequency-generating device such as a turbine flowmeter, data transmission
in a current format proportional to flow is obtainable.
The Modulated Carrier produces a carrier frequency in conjunction with a RF pickup coil,
detects and amplifies the shift in the carrier frequency (modulation) that occurs with the
passage of magnetic material and generates a squarewave pulse with each shift in carrier
frequency. The pulse’s frequency is proportional to the input frequency and is converted
linearly to a representative current output through a load. The full-scale frequency of 353500Hz is selectable via S1. LED D1 illuminates when a signal is present.
The Modulated Carrier principle introduces no drag on the passing magnetic device. Therefore,
extension of the low end of a flowmeter’s nominal linear range is realized. This parameter is
particularly useful when measuring a low mass gas. Installation of the SP720-2 requires only 2
wires because it is a true 2-wire transmitter in that input power and analog output utilize the
same wires.
Sponsler, Inc.
SP720-2 Transmitter
pg
3
DOC# MN-720
A)
Connect DMM positive lead to power supply positive and the DMM negative
lead to J1-3, Set DMM function to mA DC
B)
Connect power supply negative lead to J1-5
C)
Connect RF pickup coil to J1-1, 2
D)
Connect oscilloscope positive and negative leads to J1-1, 2 respectively
E)
Set S1 for desired full scale frequency range
F)
carrier sinewave
G)
Adjust ‘ZERO’ (R25) for 4.00mA DMM indication
H)
Disconnect oscilloscope @ J1-1,2. Connect frequency generator positive and
amplitude to 5Vp-p (0-5v) and frequency to the desired full scale point
I)
Adjust ‘SPAN’ (R20) for 20.00mA DMM indication
Reduce signal amplitude to frequency generator to zero, adjust ‘ZERO’ (R25)
for 4.00mA DMM indication if necessary
K)
Adjust signal amplitude of frequency generator to 5Vp-p, adjust ‘SPAN’ (R20)
for 20.00mA DMM indication if necessary
Adjust frequency of frequency generator to exactly 50% of the maximum
75% points
BENCH TEST CALIBRATION PROCEDURE
Required Equipment: Power Supply 5-28 VDC, Digital Multimeter (DMM), Frequency
Generator, Frequency Counter, Oscilloscope
Test Procedure:
Turn power supply ‘ON’. Observe oscilloscope displays 50KHz ± 5KHz 6Vp-p
negative leads to J1-1,2 respectively, set function to squarewave and
J)
L)
frequency point in step H, DMM should indicate 12.00mA ±.06, repeat 25%,
To check for linearity @ any frequency point incorporate the following formula (F/F max X 16) + 4 = mA
Example: Assume maximum frequency point = 2000Hz (20.00mA point)
Check for linearity @ 750Hz point
750/2000 = .375
16 X .375 = 6
6 + 4 = 10 DMM should indicate 10.00mA @ 750Hz input
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