Skip to main content
Tenselo Tenselo Water Engineering Tools
4–20 mA Loop Scaling

Loops that read true.

4–20 mA scaling, sensor ranging and loop budgets without the head-scratching. Built for the instrument techs and electricians who commission water plants.

A worked example

4–20 mA current loop

Linear scaling + loop resistance budget

The figures shown are an indicative worked example. Every result Tenselo produces shows the inputs it used and the method behind it, so the work can be checked rather than taken on trust.

Inputs
Sensor range 0 – 10 bar
Loop supply 24 V
Loop resistance 250 Ω
Cable run 300 m
Results
0 bar
at 4 mA
10 bar
at 20 mA
0.625
bar / mA
600 Ω
Max loop R
12.5 V
Headroom
2-wire
Loop type

Why it matters on the job

Scaling that's right

Engineering units mapped to 4–20 mA so SCADA reads exactly what the sensor sees.

Loops that drive

Resistance budget vs supply checked so the transmitter has the headroom to work.

Signals that survive

Cable run, volt-drop and noise margins sorted before you energise.

What is in this category

14 Instrumentation & Control calculators

Every calculator in this category, by its reference code. Running them needs a Tenselo subscription — subscriptions open soon.

  • INS-001 4-20 mA Loop Resistance Budget

    2-wire (loop-powered) transmitter: will the supply drive 4-20 mA through the sense resistor, barrier & cable?

  • INS-002 Analog Signal Scaling

    Convert 4-20 mA / 0-10 V / 1-5 V / raw counts to/from engineering units, with PLC raw scaling (8/12/16-bit) & under-range

  • INS-003 DP Flowmeter Square-Root Scaling

    Differential-pressure flow (orifice/venturi) where flow is proportional to sqrt(DP) - signal <-> flow with low-flow cutoff

  • INS-004 Flowmeter K-Factor / Pulse Scaling

    Pulse-output flowmeter (turbine/paddlewheel/mag): K-factor -> flow rate & totalised volume, both ways

  • INS-005 Flowmeter Straight-Length

    Upstream/downstream straight pipe a flowmeter needs for accuracy

  • INS-006 Level Sensor Range & Scaling

    Measuring span, 4-20 mA scaling, resolution and top/bottom blanking

  • INS-007 Pressure Transducer Range Selection

    Pick a sensor range from normal/surge pressure with good turndown and accuracy

  • INS-008 Control Transformer VA Sizing

    Size a control/isolation transformer for the continuous (sealed) load and the inrush of the largest device

  • INS-009 Instrument Air Demand & Receiver

    Air demand, receiver volume and compressor FAD for pneumatic actuators

  • INS-010 PLC I/O & Control Panel Power

    I/O card count (with spares) and the 24 V DC panel supply

  • INS-011 RTU Solar / Battery Autonomy

    Battery Ah and solar watts for an off-grid telemetry outstation

  • INS-012 VSD / Soft-Starter Selection

    Drive & soft-starter sizing, start method vs DOL inrush (IEC 60947-4 / 61800)

  • INS-013 SCADA Poll / Scan Capacity

    Scan-cycle time, channel utilisation and how many RTUs fit the poll rate

  • INS-014 Telemetry Data Budget

    Monthly cellular data per remote site from poll rate and payload

Subscriptions open soon

Register your interest

Tenselo is in private beta with Australian water professionals. Leave your details and we’ll let you know the moment plans go on sale — no obligation, and we won’t pass your details to anyone.

We’ll only email you about Tenselo. Unsubscribe any time. See our Privacy Policy.