Liquid Controls IT275N - Manual (Page 4)

Sponsler, Inc. IT275N Remote Totalizer & Rate Indicator pg. 4 DOC#: MN-275N-A
INTRODUCTION
General
The Model IT275N Industrial Remote Totalizer & Rate Indicator is a battery powered device that
provides flow totalization & rate in any engineering unit. Total is displayed via an 8-digit liquid crystal
display; Rate via a 6-digit liquid crystal display. The Totalizer Reset function is accomplished externally
by a magnetic field. This particular feature retains the unit’s integrity permitting complete operational
control in hazardous environments.
Negatives previously associated with LCD’s – poor cold temperature performances, condensation which
is a byproduct of heaters and display ghosting have all been eradicated by incorporating a low
temperature coefficient LCD (-35
o
C). All monolithic and discrete devices of the IT275N have
temperature specs of –40 to 125
o
C.
In addition the IT275N provides 1 analog interface output. The 4-20mA loop control extracts no power
from the loop.
Theory of Operation
The IT275N amplifies and shapes the incoming pulses generated by the turbine's response to flow. The
amplified pulse train is then factored and divided to produce a totalized display in the desired
engineering unit. In the rate circuit, the divided pulse train is factored by a phase locked loop (PLL) and
combined with a timebase circuit for absolute accuracy. This configuration permits the calibration factor
to be universal for the total and rate displays.
Calibration
Field calibration is accomplished by incorporating a calibration factor based on the turbine's K-Factor.
The calibration factor range is .00000001 – 1.9999. The calibration factor is entered via 4 BCD
switches, a divider switch and a ‘0-1’ switch for the total and rate functions.
Calibration of the 4-20mA loop control is established by a F/S Frequency selector switch in conjunction
with the zero and span adjustments. 4-20mA calibration is independent of the calibration factor entered
for total & rate display units.
(SPONSLER, INC. STRONGLY RECOMMENDS THOROUGH REVIEW AND UNDERSTANDING OF
THIS MANUAL PRIOR TO INSTALLATION)