Multi-Pump Systems & Duty Rotation
Several pumps behaving as one — sharing the work and covering for each other.
A pump room with more than one pump usually fails in one of two ways: the lead pump does all the hours and dies early, or the standby seizes because it never ran. Putting every pump under one controller fixes both. The work is shared, extra pumps join only when they are needed, and a pump that trips hands its duty to the next healthy one — automatically.
Multi-pump controller · duty rotation · lead lag pumps · pump changeover · VFD pump control
What makes it work
The parts of the diagram above that are doing the real work.
Duty that rotates
The lead role moves from pump to pump, so the set wears evenly and the standby is a machine that has actually been run. A multi-pump set balances run time; a twin set alternates the lead every start.
Pumps stage in, not slam in
When one pump cannot keep up, the next is started after a staging delay, and it drops back out when demand falls. Starts are spaced out, so the set never takes its combined starting current in one instant.
Changeover on fault
A pump that trips — dry run, overload, a phase fault — hands its duty to the next healthy pump. The fault is logged and pushed to the app, so it is reported rather than discovered.
The control logic
One decision for the whole set, made against one reading — line pressure or tank level.
- Up to six pumps on one RS485 bus, each on an APCON driver or a variable frequency drive
- Drives are called first: the VFD trims the last few percent and fixed-speed pumps stage in behind it
- Run time balanced across the set, with an option to start the smallest pump first
- A maximum-working-pumps limit, so the set never draws more than the supply or the header can take
- A staging delay between starts — 30 seconds by default — so the set never hunts at the margin
- PID, proportional or time-delay control, the same rule for every pump in the set
- Every protection armed separately on every pump, so one pump's fault never stops the set
What you set
- Pumps in set
- Max working pumps
- Staging delay
- Control mode
- Setpoint
- Smallest pump first
How it is done
Every step below is a retrofit on the system you already have — no replacement pumps, no civil work.
- 1
Survey the set as it is
We list every pump, its starter and what it serves — pressure, transfer or both — and decide which machine gets a drive and which stays direct-on-line.
- 2
Put each pump on a driver
Each pump gets an APCON driver or keeps its VFD, and every driver joins one RS485 bus. One shared reading — header pressure or tank level — is what the whole set decides against.
- 3
Set the rules once
How many pumps, how many may run together, the staging delay, the setpoint and the control mode — at the controller or from the app.
- 4
Watch the set, not the pumps
The app shows which pump leads, which are staged in, run hours side by side and every changeover — so uneven wear or a struggling pump shows up as a trend, not a breakdown.
What it takes
- Twin Motor Driver for two pumps, or the Multi Pump Controller for up to six
- An APCON driver or a supported VFD on each pump in a larger set
- A pressure transmitter on the header, or level sensors on the tanks
- The Devyami app for lead and lag status, run hours and changeover history
What you get
- Even wear — run hours within a few of each other
- A standby that works on the day it is needed
- No combined inrush: starts are staggered
- Every changeover and trip logged with its cause
Controllers that do this
Engineered and built by us — each one the starter, the controller and the protection in a single box.
Twin Motor Driver
Two pumps from one controller — duty shared, each motor protected on its own.
View product →Multi Pump Controller
Up to six pumps — drives and direct-on-line — running as one system.
View product →
Motor Driver
Starter, controller and motor protection for one pump — single or three phase.
View product →Questions, answered
How many pumps can one controller run? ＋
A Twin Motor Driver runs two pumps from one box, with one or both allowed to run together. The Multi Pump Controller runs up to six, each on its own APCON driver or variable frequency drive, all on one RS485 bus.
Does duty rotation actually matter? ＋
Yes. Without it the lead pump does all the work and fails years before its standby, which has meanwhile seized from never running. Rotating duty spreads the hours and exercises every machine, so the standby actually works on the day it is needed.
Can I mix VFD and fixed-speed pumps in one set? ＋
Yes — it is the usual answer. The controller calls the drive first so it trims the last few percent, and stages the fixed-speed pumps in behind it as demand grows. Danfoss and Grundfos drives join the set over Modbus alongside APCON drivers.
More water automation
Every automation runs on the same APCON controllers — and keeps working without the internet.
Pump Motor Protection
Dry run (with and without a sensor), overload, under load, under and over voltage, phase loss, over-cycling and over-run — nine protections armed on every APCON controller, logged with their cause.
How it is done →Pump Starters — DOL, Star–Delta & VFD
DOL, star–delta or a variable frequency drive: how each one starts a pump motor, the starting current it draws, and which one your pump needs — with automation and protection on top of every one.
How it is done →Also automated
Want multi-pump systems & duty rotation on your site?
Tell us what your pump room looks like today — we design, retrofit and stand behind the whole system.