Quanzhou Ausenist Technology Co., Ltd How to Use YS620 Relay and Open-Collector Outputs in a Pump Control Panel
The YS620 provides a programmable relay output on TA/TB/TC and a programmable open-collector output on MO with GND as its common reference. The manual lists relay contact capacity as AC 250 V/3 A or DC 30 V/1 A and provides selectable status functions. Correct integration requires checking the exact model, load type, PLC input circuit, common reference, output logic, delay settings and required behavior when the VFD loses power.
Why This Application Needs Pump-Specific Engineering
A status output looks simple until it is expected to stop a process, call a standby pump or report a fault to a building system. Relay contacts are isolated switching elements, while an open-collector output generally requires an external circuit and correct polarity. The signal can also be logically correct but operationally misleading: a RUN indication may disappear on power loss, a FAULT indication may never energize without control power, and a sleep state is not the same as a stopped or failed pump. Panel engineers should start from the required system meaning, then choose the terminal, function and fail-safe philosophy. Qualified personnel must use the exact YS620 manual and applicable electrical practices.
Engineering Decisions and Evidence
Choose relay or MO from the receiving circuit
TA/TB/TC provide relay contacts; MO is the programmable transistor-style output referenced to GND.
Evidence to collect: PLC input specification, voltage, current, polarity, isolation and cable route.
Risk if ignored: The wrong interface can damage an input or produce an unreliable status.
Engineering decision: Draw the complete circuit and verify ratings before wiring.
Respect contact ratings and load type
The manual's relay rating is a maximum contact capacity, not permission to switch every inductive device directly.
Evidence to collect: Actual coil inrush, steady current, voltage and suppression recommended by the load manufacturer.
Risk if ignored: Inductive loads can create arcing, interference and shortened contact life.
Engineering decision: Use an interposing relay or suitable suppression when engineering review requires it.
Define what each status means
Available selections include device on, fault, frequency states, standby and sleeping among other documented options.
Evidence to collect: Cause-and-effect table describing when the signal becomes valid and what the PLC does next.
Risk if ignored: A generic RUN lamp may be mistaken for confirmed water flow or healthy pressure.
Engineering decision: Name signals precisely, such as drive-fault indication or sleep status, and do not infer hydraulic proof.
Design for loss of VFD power
An output that depends on powered electronics cannot actively communicate after all VFD control power is lost.
Evidence to collect: PLC interpretation of open, closed and missing signals during normal, fault and power-off states.
Risk if ignored: The supervisory system may report healthy when the VFD is actually de-energized.
Engineering decision: Use normally energized logic, separate power monitoring or redundant contacts when the risk justifies them.
Use output delay intentionally
YS620 parameters include delay settings for relay and MO outputs.
Evidence to collect: Required debounce time, alarm persistence and process response time.
Risk if ignored: Excess delay can hide a real fault; zero delay may transmit nuisance transitions.
Engineering decision: Set delay from the receiving-system requirement and test both activation and clearing.
Separate status from command wiring
DI terminals command functions; output terminals report selected states. Mixing these roles creates difficult feedback loops.
Evidence to collect: I/O list, terminal drawing, source and sink references and isolation boundaries.
Risk if ignored: A wiring error can create unintended starts or repeated resets.
Engineering decision: Review every conductor against the cause-and-effect matrix before energizing.
Confirm the exact relay behavior by model
The manual notes a factory-default relay-output validity distinction around 4 kW models.
Evidence to collect: Exact YS620 model, released parameter record and bench test of the ordered unit.
Risk if ignored: Assuming one default across all ratings can make a production panel behave differently.
Engineering decision: Treat defaults as starting information; explicitly configure and verify the required output.
Test every PLC interpretation
A changing terminal voltage is not enough; the supervisory software must display and act correctly.
Evidence to collect: Test sheet covering run, sleep, stop, fault, sensor loss and VFD power loss.
Risk if ignored: Incorrect inversion or stale alarms can mislead operators and maintenance staff.
Engineering decision: Record physical terminal state, PLC bit, HMI message and final process action for each test.
Control electrical noise
VFD motor cables and switching devices can interfere with low-level control circuits.
Evidence to collect: Cable segregation, grounding, shield practice and observed input stability during acceleration.
Risk if ignored: False status changes can trigger alarms or unwanted sequencing.
Engineering decision: Follow panel standards and investigate noise at its source rather than masking it with long delays.
Verification Workflow
| Stage | Action | Acceptance evidence |
|---|---|---|
| Function | Write the required system meaning | Cause-and-effect approved |
| Interface | Check relay or MO electrical fit | Circuit ratings verified |
| Configure | Select function and delay | Parameter revision recorded |
| Wire | Apply segregation and references | Continuity inspection passes |
| Simulate | Create every operating state | PLC and HMI agree |
| Fail safe | Remove VFD power | Supervision reports correctly |
Information Buyers Should Send With the RFQ
- Exact ys620 model and power
- Plc or controller input circuit
- Desired status and fail-safe meaning
- Load voltage, current and inductive characteristics
- Panel control voltage and grounding method
- Required output delays
- Hmi messages and automatic actions
- Oem terminal labels and wiring-document format
Recommended production test
For each panel, power the YS620 in a safe test arrangement and confirm the assigned output at stop, run and sleep. Create the permitted fault input or simulation, then confirm terminal continuity or voltage, PLC bit, alarm text and reset behavior. Finally isolate VFD power while leaving the PLC powered. This last test often exposes fail-safe assumptions that normal commissioning misses. Attach the signed test to the panel serial or batch record.
OEM documentation
A controlled OEM pack should contain the I/O list, terminal drawing, parameter values for U2-15 or U2-16 as applicable, output delays, PLC logic version and acceptance results. If the exact YS620 power rating changes, recheck terminal defaults and the electrical design. Ausenist can support model and parameter clarification, while the panel builder owns the complete circuit and compliance review.
Remote support evidence
When an output appears wrong, report the selected function, measured state at the terminal, VFD display state, PLC input voltage and whether the problem follows run, sleep, fault or power loss. A wiring photo alone cannot show logic inversion or a mismatched common. Structured evidence lets Ausenist separate configuration, circuit and supervisory-software causes quickly.
Frequently Asked Questions
Can the YS620 relay directly switch a contactor coil?
Check the real coil inrush and load type against the contact rating and panel practice. An interposing device may be appropriate.
Is MO a dry contact?
No. The manual describes MO as a programmable output with GND as the corresponding common; design the receiving circuit accordingly.
Can a RUN output prove that water is flowing?
No. It proves only the configured drive state. Flow or pressure proof needs suitable process feedback.
Which contact is normally open?
The YS620 manual identifies TA/TB as normally open and TB/TC as normally closed; verify the exact ordered unit and drawing before use.
Why does the PLC alarm when the VFD enters sleep?
The selected status may not distinguish sleep from stop as intended, or the PLC logic may interpret loss of RUN as failure. Review the state matrix.
Ask Ausenist for an Application Review
Send Ausenist the YS620 model, intended output function, PLC input diagram, control voltage, load data, fail-safe requirement and I/O list. Our pump-control specialists can help confirm the relevant YS620 terminal and parameter information for your OEM panel.