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Equipment & hydraulic-magnetic breakers
We have handled 0 equipment & hydraulic-magnetic breakers part numbers, 0 of them in stock right now. This page lists all of them — including the ones we do not currently hold.
Choosing one: a hydraulic-magnetic breaker is not the breaker you are used to
Written for people looking for a substitute. We are not the manufacturer — what follows is how this class of part works and what usually matters when substituting. Always confirm against the datasheet.
The trip point does not drift with ambient temperature — that is why it gets specified
A thermal-magnetic breaker works off a bimetal strip: hot ambient trips early, cold trips late, and the datasheet carries a derating curve. A hydraulic-magnetic breaker moves a core through a damping fluid, so the trip point is set by that damping and is essentially temperature-independent. That is why engine rooms, telecom cabinets and outdoor power gear call for them. Substitute an ordinary thermal-magnetic part and it tests fine on the bench, then starts nuisance-tripping on a hot day at full load.
The delay curve matters as much as the current, and it is encoded in the part number
Airpax-style part numbers carry the delay characteristic in the string and on the label (the DELAY code you see printed). Two 35 A parts with different curves behave differently: the fast one trips on the inrush of a motor or a power module. Matching amps and ignoring the curve is the most common mismatch we see on this class of part. Photograph the whole label rather than quoting the amp rating alone.
UL 1077 and UL 489 are not interchangeable, even when they look identical
A UL 1077 device is a supplementary protector: it may only sit downstream of real branch protection. UL 489 is branch-circuit protection. The two can look exactly alike; the difference is the listing on the label. Using a 1077 part for branch protection will not pass inspection or insurance — that is a compliance problem, not a performance one.
On DC, check polarity and series requirements
DC has no zero crossing, so the arc is harder to clear. Datasheets for DC use often specify a polarity, or require poles in series to reach the stated interrupting rating. Reverse it or use one pole fewer and the arc may not clear at rated voltage — something a low-current bench test will not reveal.
Part numbers in this category
We handle this category, but there is no line-item record in the system yet. This page stays up — the part table appears here automatically once we hold or have handled stock.
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Common questions
I have an Airpax part in hand — can you match it?
Send us a clear photo of the whole label: the part-number string, the amp rating, the max voltage and the delay code are all on it. We will tell you line by line what we have and how many. If we cannot match it we will say so rather than offer you something close.
Are these new or pulled from equipment?
We label it lot by lot rather than making one blanket claim. Each lot page states the condition, the packaging and the date codes, with our own photographs. Before paying you can open the cartons yourself at the warehouse holding that lot, or have SGS / BV do it — each lot page states which warehouse holds it.
What is the minimum order?
We split lots — the minimum is 10 pieces. Taking a whole lot is meaningfully cheaper per piece. Quantity and price are per part number: send us the part number and the quantity you want and we will come back with a range rather than a round of questions.
Why is this its own category rather than sitting under breakers?
Because it is a different thing from moulded-case (MCCB) and DIN-rail miniature (MCB) breakers: different place in the system, different listings, different current range. Lumping them together fails both audiences — someone after an MCCB lands on equipment-scale parts, and someone hunting a hydraulic-magnetic replacement has no way in at all.
Are you an authorised distributor for these brands?
No, and we have never claimed to be. Stock comes from cancelled projects, plant closures and distributor clear-outs, and every lot says which. See Quality & verification.