Last Updated: 2026-10-05
Quick Answer: A DC OK relay is a supply-status signal contact, not a second power output. Before specifying it for an OEM alarm interface, verify the exact contact behavior, receiving input, external signal supply, minimum switching requirements and timing documentation. The contact cannot by itself prove that a conveyor is running, a pump is delivering water, a battery is healthy or a safety function is effective. Keep those claims separate from the power supply’s documented indication.
Separate the DC OK relay from the power output
An OEM panel drawing may place a status contact beside the supply’s DC terminals, but physical proximity does not make their electrical roles interchangeable. The power output provides energy to a compatible, appropriately assessed load. The signal contact provides a state that another circuit must interpret. Treating the two as equivalent can create an unclear bill of materials, an unsupported alarm description or an unsuitable receiving interface.
Begin procurement with two separate questions: what powers the equipment, and what information must the control system receive? A requirement such as “supply status available to the controller” is narrower than “machine operating normally.” Write that boundary into the interface specification before selecting a controller input, annunciator or telemetry channel.
Use the exact MDR-60-12 documents
The WEHO MDR-60 product page lists MDR-60-12 as a 12 V, 5 A, 60 W model. The selected mechanical specification records 40 mm width, 90 mm height and 100 mm depth. Its relay documentation describes contact closed as power on/DC normal and contact open as power off/DC fault, with a maximum contact rating of 30 V/1 A for a resistive load. These are identification and interface facts, not evidence that a particular controller or application has been qualified.
Keep the ordered unit’s nameplate, specification revision and terminal drawing together. Do not merge its nameplate AC input statement with a family operating-range entry as though they were identical wording. Differences between documents also must not be resolved by choosing the most favorable adjustment range, efficiency, overload or insulation figure. Ask for the applicable ordered-revision information before making an associated performance commitment.
The source model is MDR-60-12; it is not a relabeled 24 V variant. Compare other products only through their own verified records in the WEHO DIN rail power supply category. The outside envelope alone does not establish cable-bend allowance, ventilation clearance or service access.
Define exactly what an alarm is allowed to mean
For a DC OK relay interface, separate the manufacturer’s contact description from the OEM’s proposed message. A receiving system might display “power supply status contact open.” Calling the same event “conveyor drive failed” requires additional evidence from the drive and machine architecture. The relay description does not establish the condition of every device connected downstream.
The distinction matters during fault review. A supply-status contact can have its documented state while a separate load remains disconnected, a downstream protective device is open or a controller has not completed its start-up sequence. Conversely, an open signal path at the receiver may require investigation of the interface as well as the supply. These are review scenarios, not measured outcomes for the pictured equipment.
Do not assign a precise output-voltage threshold to “DC normal” unless exact-model documentation provides it. Do not assume a switching delay, hysteresis band, power-up sequence or response during overload. A basic closed/open description is not a complete event-timing specification.
Check the receiving input and external signal supply
Procurement should request the receiving device’s actual input specification rather than accepting “PLC compatible” as a complete answer. Relevant information includes input type, valid state thresholds, polarity requirements, source/sink arrangement where applicable, input current, filtering and the treatment of an open circuit. The supplier needs the exact interface record, not an assumed controller family.
The proposed signal circuit also needs a documented energy source. A relay contact must not be described as supplying its own signal voltage. Determine which external source the receiving interface requires and how the interface behaves when that source is unavailable. If the proposed signal source depends on the same supply being monitored, the control team must review whether the intended fault indication remains observable during that supply’s loss. No such behavior is demonstrated by a disconnected product photograph.
Keep the DC OK relay contact terminals distinct from the power-output terminals in the drawing review. Similar terminal openings do not authorize substitution of one connection for another. The relevant terminal drawing and ordered unit govern identification; this article provides no energized wiring procedure, conductor selection or terminal-torque instruction.
Verify small-current switching and the actual load type
A maximum resistive contact rating is a limit, not a guarantee for every signal circuit below that limit. Request the minimum switching voltage/current or wetting requirements, where applicable, and compare them with the actual receiving input. If the minimum requirement is undocumented, record that gap rather than inventing a value or adding an unapproved circuit component.
Also distinguish an electronic input from a lamp, relay coil, solenoid or other load. Inductive and capacitive behavior, inrush and switching duty may require different evidence than a resistive rating. The stated rating must not be promoted into permission to switch an arbitrary actuator or to feed a panel accessory directly through the status contact.
Any proposed interface device, suppression component or logic change belongs in the approved engineering design. Identify its function, obtain the relevant specifications and define the verification required. Do not treat an improvised workaround as a qualified solution simply because an indicator changes state once.
Treat contact timing as a documented interface requirement
Define what the receiver must do during first start, shutdown and the intended operating sequence. Ask whether the application needs a retained event, a delayed advisory message or another defined response, then identify the evidence needed to support that behavior. Avoid selecting a delay value merely to hide an unexplained event.
The DC OK relay alone does not prove battery backup, UPS operation or uninterrupted controller power. Those functions require their own architecture and documentation. It also is not evidence of a safety-rated alarm, emergency stop or protective interlock. Safety-related requirements must be handled through the responsible qualified team’s separate design and validation process; never infer them from a general status-contact description.
An interface review should leave a clear distinction between confirmed document statements, proposed system behavior and information still required. That distinction keeps a purchasing decision from silently becoming a performance or safety claim.
Conveyor OEM alarm-interface review
For a conveyor OEM, the useful starting point is an interface list: supply status, controller status, drive status and any other signals the machine specification actually requires. Decide which requirement the supply contact addresses and which must come from another documented source. The pictured scene is an unpowered, disconnected review context, not a commissioned conveyor circuit or proof of load compatibility.
The panel team can review device identities, document revisions and the planned signal names without inventing field measurements. Keep the proposed alarm wording narrow enough that a maintenance technician knows what to investigate. Record unresolved receiving-input and switching questions before the bill of materials is released.
Remote water-pump telemetry assessment
A remote telemetry interface introduces a different information boundary. A message about supply status does not prove that a pump is running, water is flowing or a communications link is functioning. Each proposed statement needs an identified source. Do not use a single status contact as a substitute for all of them.
For the hypothetical telemetry review, request the receiver’s input requirements and proposed behavior when its own power or communications path is unavailable. Identify which observations would remain local and which could be reported remotely. The illustration shows an unpowered, disconnected assessment only; no paired receiver, field test, transmission result or pump requirement is claimed.
Make document gaps visible before procurement release
An effective review packet connects each proposed claim to its evidence. Include the exact supply model, readable nameplate record, applicable mechanical and terminal drawings, contact description, receiving-input data and external signal-source information. Add the contact-load assessment, minimum switching requirements and timing information—or explicitly mark each missing item.
Keep review outcomes distinct. “Documents collected” does not mean “interface verified,” and “interface verified” does not mean “machine functionality proven.” Any verification performed later should retain its method, conditions, responsible reviewer and acceptance basis. This guide reports no such test results.
If a document conflict remains, ask WEHO technical support for the exact ordered-model and revision clarification, supplying the nameplate and the disputed document entries. Procurement can then record the decision and its limits instead of passing an unresolved assumption into production.
Key Takeaways
- A DC OK relay contact and the DC power output have different roles.
- Use the exact MDR-60-12 identity and applicable revision; do not relabel it as another voltage model.
- Check the receiver, external signal source, minimum switching requirements and actual load type.
- Do not invent voltage thresholds, timing, field results or universal PLC compatibility.
- Supply status does not prove load operation, battery health, communications delivery or a safety function.
Kesimpulan
A DC OK relay is useful when its meaning and receiving interface are documented precisely. Keep power delivery, contact state and application-level conclusions separate. For OEM panels, an evidence-based review makes alarm descriptions more actionable and purchasing decisions more traceable, without promising behavior that has not been specified or verified.
Frequently Asked Questions
Is the DC OK relay a second power output?
No. It is a supply-status signal contact, not a source of load power or its own signal voltage. The receiving interface and any external signal supply must be specified and assessed separately from the supply’s DC output.
What does the MDR-60-12 contact documentation say?
The reviewed relay documentation describes closed as power on/DC normal and open as power off/DC fault, with a maximum rating of 30 V/1 A for a resistive contact load. That description does not establish an exact voltage threshold, switching delay, universal controller compatibility or the operating condition of downstream equipment.
What should be checked before connecting the signal to a PLC or telemetry input?
Obtain the exact receiving-input requirements, proposed external signal source, valid state thresholds, polarity or source/sink arrangement where applicable, input current and filtering. Also request minimum switching or wetting requirements and timing information for the ordered supply revision. Mark missing information explicitly rather than inventing values.
Can the contact prove that a conveyor or water pump is operating correctly?
No. The documented supply-status condition is narrower than machine operation, water flow or communications delivery. Each application-level claim needs its own identified signal source and verification. The article’s conveyor and water-telemetry images depict unpowered, disconnected interface reviews, not commissioned systems or measured results.
Does the maximum resistive rating permit switching a relay coil or actuator?
Not without an appropriate engineering assessment. A maximum resistive rating does not establish suitability for inductive loads, capacitive loads, inrush or a particular switching duty. Obtain the actual load information and applicable contact requirements; do not treat the status contact as an arbitrary accessory-power path or a safety-rated interlock.
