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Application solution · WATER UTILITY

Intelligent Constant-Pressure Water Supply

Quick answer

Can a VFD maintain constant water pressure without an external PLC?

A basic pump system can use the Kinco KC100-W1 built-in PID to regulate pressure and coordinate one master with up to five slave pumps, while a GREEN HMI adds monitoring and MQTT. The review checks pump count, sensor input, hydraulic sizing, protections and BMS needs.

Building water-supply integrators evaluating built-in PID, master-slave cascading and remote monitoring for residential, community or HVAC pump systems; hydraulic architecture and rooftop-tank implications remain subject to engineering review.

Reference architecture · Model-specific review

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Kinco KC100-family variable-frequency drive
KC100-family VFD shown as a candidate component, not the complete pump-control system.

Control problem

What must this application control?

Control Topology Options

  • Multi-pump parallel: 1 variable-speed (PID master) + N fixed-speed slaves — economical for medium/large systems
  • One-to-one: each pump on its own drive — better redundancy, simpler wiring, fits smaller systems
  • KC100-W1 cascading: up to 1 master + 5 slaves with automatic pump rotation

Pressure Sensing & Built-in PID

  • 4–20 mA pressure transducer; range selected from operating and transient pressure, sensor datasheet and site review
  • The transducer may connect directly when the exact KC100-W1 input and reviewed topology support it; external-control requirements remain subject to review
  • Built-in PID executes closed loop locally on the inverter

Safety & Energy Functions

  • Anti-freeze protection
  • Dry-run / water-shortage detection
  • Over-voltage / under-voltage protection

How the control stack fits together

Four scoping blocks show the review path; they are not a wiring diagram.

  1. Step 1

    Pump-control topology

    Choose the multi-pump master-slave route or one-drive-per-pump route from the required economy, redundancy and wiring boundary.

  2. Step 2

    Pressure feedback & PID

    Review the pressure-transducer range, direct KC100-W1 feedback connection and built-in PID scope against the pipe network.

  3. Step 3

    Supervision layer

    Select the GREEN or FUTURE HMI, MK IoT unit or optional AK PLC only where the documented site, BMS or SCADA scope requires it.

  4. Step 4

    Signal & motor wiring

    Confirm pressure-signal separation, shielded motor cabling, RS485 termination and the anti-freeze and dry-run input wiring.

Pump sets, isolation valves and headers lined up along a plant-room wall
Customer site — pump sets and headers in a plant room.

Bill of materials

Use this table to compare component roles, exact model names and key specifications before application review.

Intelligent Constant-Pressure Water Supply recommended bill of materials
RoleComponentKey spec
DRIVEKinco KC100-W1Dedicated HVAC/water VFD · built-in PID · 1M/5S cascade · 4DI/1AI/1DO/1AO/1Pulse/1RS485
HMIKinco GREEN Series HMIMulti-size · IoT cloud · MQTT · trend/alarm log
IOTIoT all-in-one controllerOptional · HMI + PLC + M-IoT for unmanned remote sites · auto/manual mode · model confirmed per project spec
SENSORPressure transducer 4–20 mAIP rating and pressure range selected from the site operating and transient conditions
PSU24 VDC power supplyFor HMI / sensor loop / control logic
OPTIONALExternal Kinco AK PLCOptional for reviewed pump-count, multi-zone or BMS/SCADA scope; fire-pump systems require a separately certified architecture

Configuration summary. For a reviewed basic pump system, KC100-W1 built-in PID can run a one-master, up-to-five-slave cascade. GREEN HMI can add MQTT monitoring.

This is a candidate architecture, not a quotation. BOM review checks each line against your machine, and programming support scopes the control work once the hardware is agreed.

What changes the component choice?

What we check
  • Selection: KC100-W1 may support one master plus up to five slaves in a reviewed basic topology per supplier documentation; confirm pump count, hydraulics and control scope at RFQ.
  • Selection: Review an external PLC for additional pumps, multi-zone control or documented BMS/SCADA requirements; no fire-system functionality is assumed.
  • Selection: HMI selection: GREEN series for standard residential/commercial water rooms; FUTURE for large municipal substations needing electronic-signature audit; MASS for cost-sensitive small buildings.
  • Selection: Evaluate an IoT all-in-one controller when the documented site scope requires remote supervision; the exact model is confirmed per project spec.
  • Selection: Pressure transducer range typically 1.5× expected operating pressure (e.g., 0–10 bar for 5–6 bar operation) — lower range increases resolution but risks saturation under transient events.
  • Wiring / protocol: 4–20 mA pressure transducer loop wired in a separate cable bundle from VFD motor output (EMI isolation)
  • Wiring / protocol: Master-slave RS485 cascade requires shielded twisted pair with proper termination at both ends
  • Wiring / protocol: Each pump motor cable shielded; output filter recommended for runs >50m to protect motor insulation
  • Wiring / protocol: Anti-freeze sensor and dry-run input wired to KC100-W1 DI ports per manual
  • Migration: Eliminating rooftop water tank: requires hydraulic re-design (boost pump curve sizing, pressure setpoint per floor) and likely new riser piping.
  • Migration: Replacing Siemens / Schneider + external PID controller: PID parameters cannot be directly carried over — re-tune on-site based on actual pipe network volume and pump curve.
  • Migration: Existing motor insulation should be VFD-compatible (Class F+); legacy motors may need replacement.
  • Migration: Cabinet may need rework for KC100-W1 heat dissipation and EMC filter installation.
Where it may not fit
  • Constant-flow systems running near rated load 24/7 (limited energy-saving benefit)
  • Industrial process water with cyclic high-frequency setpoint changes (PID-on-inverter may be slower than dedicated process controller)
  • Sites with severe power-quality issues (deep voltage dips, dirty grid) unless input chokes / line filters are added
  • Fire-pump systems requiring UL/FM certifications specific to fire protection — those need a dedicated certified stack
  • Component certificates do not certify the finished machine; the responsible builder or integrator retains system-level validation.

Frequently asked

Can KC100-W1 control multiple pumps without an external PLC?

A reviewed basic topology can use built-in PID with one master and up to five slave pumps. Pump count, hydraulics, protection and any external PLC requirement are confirmed during engineering review.

How does this compare to a rooftop water tank system?

A VFD-controlled pressure system can be evaluated as an alternative to a rooftop tank, but tank removal depends on hydraulic design, code requirements, redundancy and site conditions. Structural, hygiene and energy effects must be assessed against the actual baseline.

Can this integrate with existing building SCADA / BMS?

KC100-W1 publishes Modbus RTU support, and GREEN HMI publishes MQTT capability. SCADA/BMS compatibility, gateway requirements, BACnet or KNX support and data mapping must be confirmed for the exact architecture.

Application review

Check this architecture against your machine

Send the payload, duty, voltage, protocol, safety scope and any existing part numbers you already know.

Request engineering review

Limits. These figures describe the stated configuration, not Automation Liberty customer results. This is a candidate architecture; exact model, compatibility, certification, availability and commercial scope are subject to engineering review and confirmed at RFQ.

Independent engineering and sourcing partner. Product names and trademarks are the property of their respective owners and are used for identification only.

Why no list price? Every quote follows an engineering review of your application — you get a validated price, not a catalog number.

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