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Author: Site Editor Publish Time: 2026-08-21 Origin: Site
In booster pump and water pressure systems, reliable pump sequencing is essential for maintaining stable operation, balancing pump usage and reducing unnecessary mechanical wear. The HSR-S Booster Pump Sequencing Relay provides an effective control solution for systems using up to three pumps, combining pressure-demand control, automatic pump rotation and individual thermal protection monitoring in one compact DIN-rail device.
The HSR-S is designed to automatically determine how many pumps are required according to signals from three pressure switch inputs: P1, P2 and P3.
When P1 is activated, one pump is required.
When P1 and P2 are activated, two pumps are required.
When P1, P2 and P3 are activated, three pumps are required.
This allows the controller to adapt the number of operating pumps to the actual pressure demand of the system.
Instead of operating all pumps continuously, the HSR-S automatically selects the required number of available pump outputs, helping create a more efficient and organized multi-pump control system.
One of the key functions of the HSR-S is its automatic pump sequencing capability.
For one-pump and two-pump operation, the controller periodically changes the active pump or pump combination according to the preset DT rotation interval. This helps distribute operating time between the available pumps instead of repeatedly using the same pump first.
The DT interval can be selected from:
10 min · 30 min · 1 h · 3 h · 6 h · 12 h · OFF
When DT is set to OFF, automatic time-based rotation is disabled and pump operation is controlled only according to pressure demand and pump availability.
By periodically rotating the operating pumps, the HSR-S helps balance accumulated operating time and reduce uneven mechanical wear across the pump group.
Reliable pump control requires more than simply switching outputs. Each pump must also be available and protected before it is allowed to operate.
The HSR-S therefore provides three independent thermal protection inputs:
S1 → H1
S2 → H2
S3 → H3
Each S input is connected through the normally closed auxiliary contact of the corresponding thermal overload relay.
Under normal operating conditions, the thermal overload contact remains closed and the corresponding pump output is permitted to operate. If the thermal overload relay trips, the contact opens, the corresponding S input is de-energized and that pump is immediately excluded from the operating sequence.
Importantly, a fault affecting one pump does not necessarily stop the entire system. Other pumps whose thermal protection inputs remain energized may continue operating according to system demand.
This design improves system availability while maintaining individual protection for each pump.
The HSR-S does not simply follow a fixed H1-H2-H3 operating order. It evaluates whether each pump is available through its corresponding S input.
If one pump becomes unavailable, the controller automatically excludes that output and continues sequencing among the remaining available pumps.
For example, during one-pump operation, the normal sequence may be:
H1 → H2 → H3 → H1
If S2 is not energized, H2 is unavailable and the sequence automatically becomes:
H1 → H3 → H1
This allows the system to continue operating without requiring the entire booster pump system to shut down because of a single unavailable pump.
The front panel provides dedicated LED indicators that allow operators to quickly understand the current operating condition.
P1, P2 and P3 indicate the status of the pressure switch inputs and therefore the current pump demand.
S1, S2 and S3 indicate whether the corresponding pump protection circuit is available.
H1, H2 and H3 indicate the energized state of the corresponding relay outputs.
An additional ON indicator shows that the controller is powered.
This clear status layout makes commissioning, inspection and troubleshooting easier in multi-pump installations.
The HSR-S is particularly suitable for applications requiring automatic control and alternation of multiple pumps, including:
Booster pump systems
Water pressure boosting systems
Multi-pump water supply systems
Building water supply systems
Pressure-controlled pump installations
Pump control panels
Industrial water supply systems
Its three pressure demand inputs, three individual protection inputs and three pump outputs make it especially suitable for systems where pump operation must automatically adapt to changing water demand.
The HSR-S combines several important pump-control functions in one device:
Automatic control of 1, 2 or 3 pumps
Three pressure switch inputs
Three independent thermal protection inputs
Three pump relay outputs
Automatic pump sequencing
Automatic pump rotation
10-minute to 12-hour adjustable rotation interval
Automatic exclusion of unavailable pumps
Individual pump fault isolation
Clear LED operating status indication
DIN-rail installation
For installers and panel builders, this reduces the complexity of implementing multi-pump sequencing logic using multiple conventional relays and timers.
For system operators, automatic pump rotation helps distribute operating hours more evenly among available pumps.
In a multi-pump installation, reliable operation depends not only on starting pumps when pressure demand increases, but also on deciding which pumps should operate, when they should alternate and what should happen if one pump becomes unavailable.
The HSR-S Smart Booster Pump Sequencing Relay integrates these control functions into a single compact controller.
By combining pressure-demand control, automatic pump sequencing, timed pump rotation and independent thermal protection monitoring, HSR-S provides a practical solution for reliable and efficient control of up to three booster pumps.
HSR-S – Smart Sequencing for Reliable Multi-Pump Control.
