Liquid Controls IT275N - Manual (Page 10)

Sponsler, Inc. IT275N Remote Totalizer & Rate Indicator pg. 10 DOC#: MN-275N-A
Example #8: Actual = 50
Displayed = 52
C.F. = .4000
New C.F. = 50/52 x .4000
= .9615 x .4000
= .3846
On the IT275N PCB:
Set S5@3, S6@8, S7@4, S8@6
In the above example, .9615 denotes that the meter is operating 4% fast. Multiplying by the present
C.F. (.4000) by the Actual: Displayed Ratio (.9615) effectively reduces the error by decreasing the C.F.
by 4%.
Example #9: Actual = 52
Displayed = 50
C.F. = .4000
New C.F. = 52/50 x .4000
= 1.04 x .4000
= .4160
On the Factoring PCB:
Set S5@4, S6@1, S7@6, S8@0
In the previous example, 1.04 denotes that the meter is operating 4% slow. Multiplying the present C.F.
(.4000) by the Actual: Displayed Ratio (1.04) effectively reduces the error by increasing the C.F. 4%.
4-20mA Analog Output
The IT275N provides a 4-20mA loop control that is proportional to the flow rate. The frequency-current
converter output is intended to control a 4-20mA loop, but will transmit a 4-20mA signal into a load if an
external excitation voltage is provided.
The IT275N requires 5.6V of the loops total voltage; therefore, if a 250 ohm sense or load resistor is
incorporated the minimum loop or excitation voltage must be 10.6V, 5.6V + (.02 x 250). The maximum
loop or excitation is 57.6V, 56.6V + (.004 x 250).
Minimum Loop Voltage = 5.6 + (.02 x R) Maximum Loop Voltage = 56.6 + (.004 x R)
All adjustments for the 4-20mA output are located on the IT275I PCB (Refer to FIGURE 2). The full-
scale frequency is selected by F/S range select S2, ‘0’ = 100 – 1000 Hz, ‘1’ = 1000 – 2500 Hz F/S
Frequency. To calibrate the 4-20mA output adjust ‘Zero’ (R12) for 4mA @ 0 Hz and ‘Span’ (R14) for
20mA @ the full-scale frequency. The zero and span adjustments are independent.