Hiccup protection retries the output automatically; latch-off keeps it disabled until the specified reset condition is met. That difference affects recovery time and the possibility of a connected controller restarting. Choose the behaviour for the load and process, then verify it for the exact supply and fault type. A claim such as “short-circuit protected” does not answer the recovery question.
Compare what happens after protection operates
In hiccup operation, the supply periodically attempts to start, checks the load condition, and stops again if the fault remains. Once the fault is removed, it can resume normal output. Latch-off requires an explicit reset, often removal and restoration of input power, as defined by the manufacturer. Some products also provide an enable or reset input, but that function must be documented for the actual model.
| Decision | Automatic retry / hiccup | Latch-off |
|---|---|---|
| Fault still present | Repeated attempts may continue | Output remains disabled after the trip |
| Fault removed | May recover without an operator command | Requires the documented reset |
| Equipment concern | Repeated controller starts or relay cycling | Service access and controlled restoration |
| Evidence required | Retry timing and load-start behaviour | Reset method and conditions |
These are behavioural distinctions, not a ranking of one method as universally better. An unattended monitoring node may benefit from automatic restoration. A fixture where an unexpected restart could disturb a specimen needs process controls that remain deliberate when DC returns.
Read the protection rows separately
The matching WEHO MDR-20 sheet gives a useful example. For the photographed MDR-20-12, the nominal output is 12 V and up to 1.67 A. The overload row specifies 105–160% and automatic recovery after the output is cut off. The overvoltage row specifies 120–140% with output shutdown and recovery by powering the supply again.
Those two rows describe different events on the same family. The phrase “automatic recovery” does not, by itself, specify a hiccup pulse interval or prove the exact short-circuit waveform. Likewise, the repower instruction for overvoltage should not be copied into the overload row. Ask for the offered revision’s protection description when restart timing is part of the machine requirement.
Why a flashing indicator is not a diagnosis
A repeated start-and-stop symptom can arise when the demand remains above the output capability, when a capacitive load never finishes charging during a retry window, or when another part of the equipment repeatedly removes the input or enable signal. The visible symptom alone does not prove an internal short circuit or a failed power supply.
Collect a time record of input availability, DC output at the supply, voltage at the receiver, and the receiver’s restart indication. Qualified personnel should use a suitable test procedure and measurement equipment. Compare results with the actual load-start requirement. Do not deliberately short the terminals as an informal way to identify the protection mode.
Write an acceptance sequence for the whole machine
- Define the event. Distinguish sustained overload, output short circuit, input interruption and overvoltage. They need not produce the same recovery.
- Define the permitted state. Decide which outputs must stay inactive while the controller loses power and boots again.
- Define restoration. Specify whether automatic recovery is acceptable or whether an operator reset and process re-enable are required.
- Validate with the real load. Include startup capacitance, normal demand, cable voltage drop and the receiving controller’s boot sequence.
- Retain the record. Note the full supply model, document revision, fault procedure, observed restoration and any external reset logic.
Power-supply protection is not a substitute for the equipment’s safety or restart design. A restored 12 V rail may simply mean that the electronics can operate again; it does not automatically authorise a conveyor movement, a heater output or a laboratory test to resume.
What to send with a supply enquiry
Use the WEHO catalogue to identify the proposed series, and send WEHO the recovery requirements together with output voltage, normal and startup current, receiving load type, restart policy and ambient conditions. Request the current protection table and reset instructions for the exact offered unit. The manufacturer’s power-supply FAQ provides the broader protection terminology; the model-specific document remains necessary for selection.
Common buyer questions
Does automatic recovery always mean hiccup?
No. It states that recovery can happen without the specified manual reset, but does not establish the retry waveform or timing. Obtain the actual protection description when that difference matters.
Can a latch-off supply be reset repeatedly until the load starts?
Repeated resetting does not resolve an overload, a short or an incompatible startup demand. Remove and diagnose the cause, then restore power according to the unit and equipment instructions.
Is a higher-current replacement the complete solution?
Only if the problem is genuinely insufficient capability and the replacement is compatible with the load, protection and distribution design. A larger supply can change fault energy and branch-protection requirements, so current rating alone is not a complete substitution check.
