Home » Formulas to calculate mA from PV, LRV and URV

# Formulas to calculate mA from PV, LRV and URV

The formula for calculating equivalent current (ma) from known process variable (PV), Lower range value (LRV) and Upper range value (URV).

## Formula to calculate mA from PV ##### The formula is: SPAN = URV – LRV

Where

PV          =  Process Variable
LRV       =  Low Range Value
URV      = Upper Range Value
ma        = milli ampere

Consider left side of formula for Process variable, LRV of transmitter lower range, Span is the difference between LRV & URV of transmitter ranges.

Consider right side of formula for current (ma), LRV of standard current range .i.e is 4ma,

Span is the difference between LRV (4ma) & URV (20ma) of standard current range

.i.e. 20 – 4 = 16, Using this formula we can calculate ma from pv and as well as pv from ma.

#### For example: The temperature transmitter range is 0 to 50 deg c and  known current ma is 12 then how to calculate the PV of the transmitter ?

Known values :

LRV =  0
URV =  50
mA = 12mA

Standard mA LRV and URV values are as follows –

LRV = 4mA
URV = 20mA

Span = URV – LRV
Span = 20 – 4
Span = 16

Required :

PV = ?

Formula : ##### Solution:

Put Values in Formula

PV – 0         =       mA – 4

SPAN                 16

SPAN = URV – LRV
SPAN = 50 – 0
SPAN = 50 PV – 0  =       0.5  * 50

PV  =       0.5  * 50

PV  =    25

#### Transmitter Turndown Ratio, Set Span and Zero Span January 16, 2016 at 3:28 pm

Good August 25, 2016 at 8:31 am

Dear bhardwaj sir,we have Polmon system.we controlling temp and rh in are bye it system. Now there temp showing wrong when getting 13 mA .but system range is -40 to +60 degree .how many should be there PV temp. August 25, 2016 at 8:34 am

We calculate PV from mA through u given formula mA convertor .bt temp value getting wrong.plz give me rply. August 28, 2016 at 3:06 pm August 29, 2017 at 3:47 am

Explain in detail August 14, 2019 at 12:04 pm

outstanding
plz transmitter calibration step by step full process January 4, 2020 at 4:15 pm

Instrument detail

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