Master-Auxiliary vs Synchronous Multi-Pump Control With the YS820

The YS820 supports both master-and-auxiliary control and synchronous multi-pump control. The right mode depends on how the pumps should share demand, the required pressure stability and the operating philosophy of the station.

Master-and-Auxiliary Control

In this approach, the main drive manages pressure and calls additional pumps when demand cannot be met by the active unit. Add-pump and decrease-pump delays help prevent rapid staging. This method is useful when the system should run only the number of pumps needed for current demand.

Synchronous Control

In synchronous mode, participating pumps are coordinated to operate together according to the system configuration. This may suit installations where balanced parallel operation is preferred. The pump curves, pipe layout and check valves must support stable shared flow.

Selection Questions

Question	Why it matters
Do all pumps have the same curve and motor rating?	Identical equipment is easier to coordinate.
How wide is the demand range?	Large variation may favor staged operation.
Is equal operating time important?	Rotation settings can distribute wear.
Is standby-master control required?	The second master needs pressure feedback and testing.
What happens when one auxiliary faults?	The intended bypass and alarm response must be documented.

The YS820 manual provides settings for up to four auxiliary machines and describes single-master and double-master arrangements. Each pump should normally have its own drive, with linkage terminals used for coordinated operation.

Commissioning Sequence

Verify each pump individually before enabling group control. Confirm motor direction, sensor type, target pressure and local operation. Then assign drive roles, connect the communication link, test pump addition and removal, and simulate an auxiliary fault. If a standby master is used, test the takeover rather than assuming it will work.

Request a System Recommendation

Send Ausenist the pump schedule, curves, motor nameplates, target pressure, minimum and peak flow, preferred control sequence and redundancy requirement. OEM/ODM customers can also request branding, packaging and application-specific parameter preparation after the control design is approved.

Deciding How Pumps Should Share Load

Begin with the pump curves. In staged master-auxiliary operation, the active pump changes speed until another pump is required. In synchronous operation, coordinated units may share demand. The preferred method depends on stable operating zones, minimum flow and how efficiently each pump performs at reduced speed.

Staging Thresholds

Use measured frequency, pressure and demand to determine when another unit should start. The add delay should filter short events, while the decrease delay should prevent a pump from dropping out before the system settles. Test the sequence at several demand levels rather than one fully open valve.

Rotation and Unequal Run Time

Wheel-pump timing can distribute duty, but maintenance records should still track actual hours and starts. A pump may be unavailable for service, so the sequence needs a controlled way to exclude it without corrupting addresses or roles.

Double-Master Arrangement

The standby master requires its own correct pressure feedback and the configured delay before becoming active. Document which unit controls after the original master recovers. Avoid a situation in which two drives attempt to command the group simultaneously.

Control-Mode Acceptance Test

Record pressure deviation during a pump addition, removal and role change. Confirm that every pump contributes flow, the link indication is normal and no motor exceeds rated current. Simulate a lost auxiliary and a lost master under safe conditions.

Buyer FAQ

Is synchronous mode always smoother? Not automatically. Pump matching, sensor quality and parameter settings determine the result.

Can different-sized pumps be used? A mixed system requires an engineering review of curves, sequence and safe speed range; do not assume identical behavior.

From VFD Manufacturer to Water-Control Specialist

A credible inverter expert explains the complete control loop. Electrical power is converted into controlled motor speed; the pump converts that speed into flow and head; the sensor reports pressure; and PID adjusts the next command. A problem in any link can appear to the user as a “VFD problem.”

Ausenist uses the YS620 and YS820 to address this complete chain. Model selection checks voltage and current, while application review covers pump capability, sensor quality, sleep behavior, water-shortage response and multi-pump roles. The objective is stable operation that can be commissioned and serviced logically.

This expertise is particularly useful to distributors. Instead of competing only on price, they can collect the right project data, explain functions accurately and send the factory a structured support case. That improves buyer confidence and protects the reputation of the pump package.

Engineering the Complete Multi-Pump Sequence

Multi-pump control needs a written sequence of operation. It should define which drive reads pressure, when another pump is added, when it is removed, how pumps rotate and what happens after a drive, sensor or communication fault. A diagram showing master, standby-master and auxiliary roles prevents ambiguity during wiring and service.

Hydraulic details matter as much as RS485 settings. Pumps connected in parallel need suitable curves, correctly selected non-return valves and a header that can carry the combined flow. If one pump is much larger than the others, the staging thresholds may require special review.

Acceptance testing should cover minimum demand, peak demand, rapid valve changes, sleep, wake, pump rotation, auxiliary bypass and restart after a power interruption. A redundant design is not proven until the takeover and fault responses have been observed.

Create a Technical RFQ, Not Only a Price Request

A useful request for quotation states the problem the pump system must solve. Include minimum and peak flow, pressure or head, water source, motor data, grid, sensor and control sequence. If replacing an existing drive, add its model, fault history and photographs of the installation.

International buyers should identify destination, voltage tolerance, frequency, language and required certification. For private label, provide the product matrix and forecast rather than one logo. Ausenist can then evaluate whether the requirement is standard YS620/YS820 supply, parameter preparation or engineering customization.

Review the answer for technical completeness. It should identify the proposed model and rating, assumptions, required accessories, commissioning responsibilities and unresolved questions. This makes quotations comparable and reduces later scope disputes.

Evidence of Specialist Support

Look for a logical selection form, model-specific wiring information, parameter records and a fault-data checklist. These tools show that the supplier understands how pumps, motors and VFD control interact after the sale.

Turn Each Project Into Reusable Engineering Knowledge

After commissioning, document what was selected and why. Store the pump curve, motor data, sensor, pressure target, key protection values and observed results. Note any site condition that changed the original plan. This project record supports faster and safer selection when a similar request arrives.

For distributors, a small library of verified applications is more valuable than broad unsupported claims. It allows sales teams to discuss real engineering conditions while protecting confidential customer information. It also shows where a new project requires factory review.

Ausenist's YS620 and YS820 content should follow the same principle: explain operating conditions, avoid invented performance numbers and invite buyers to submit the data needed for a confirmed solution.