ERO
ERO F1772-522-2021 X2 Suppression Capacitor, 2.2 uF 250 V AC, MKT Metallized Polyester
- 2 photos
Never used. The original pack has been opened, or the quantity was split off a full reel or tube. Leads are original and unclipped.
New old stock, open stock on the grading scaleSend the quantity you need. You get a quote back with shipping before anything is charged.
Video
Filmed on the bench. Sound is stripped from product clips.
- 0:07
Specifications
| Specification | Value |
|---|---|
| Identification | |
| Part number | F1772-522-2021 |
| Manufacturer | ERO |
| Condition | New old stock, open stock |
| Date code | 9550 |
| Package | Rectangular boxed radial, printed circuit terminals, in original carton |
| Country of origin | Not recorded |
| Family | F1772 |
| Stock number | SAW8AKF7 |
| Overview | |
| Type | Interference suppression capacitor, safety class X2 |
| Manufacturer part number | F1772-522-2021 |
| Failure mode by design | Open circuit, which is what the X2 classification requires |
| Electrical | |
| Capacitance | 2.2 uF |
| AC voltage rating | 250 V AC |
| Safety class | X2, for connection line to line across the mains |
| Dielectric | MKT, metallized polyester |
| Self healing | Yes, marked SH on the carton |
| Climatic category | 25 / 085 / 21, printed as HPF 25/085/21 |
| Polarity | None. An AC rated capacitor is not polarised |
| Compliance | |
| Standard | VDE 565-1 |
| Approval marks on carton | VDE, UL, SEV, SEMKO, DEMKO, NEMKO, FIMKO and CEI 40-7 |
| Provenance | |
| Carton code | 9550 |
| Quantity offered | One piece, in its original carton |
| Condition | New old stock, unused, carton present with legible printing |
| Physical | |
| Body | Rectangular box, yellow potting compound visible at the open end |
| Terminals | Radial wire terminals for printed circuit mounting |
About this part
An ERO F1772-522-2021 interference suppression capacitor, 2.2 uF, class X2, rated 250 volts AC. New old stock in its original printed carton, code 9550 on the box.
The class is the whole point of this part and it is not a marketing letter. An X2 capacitor is designed to be connected line to line across the mains, and it is built and tested so that when it eventually fails it fails open rather than short. An ordinary film capacitor of the same value and the same printed voltage is not a substitute and must never be used in that position: it can fail short, and a short across the line is a fire. If you are replacing an X2, replace it with an X2.
The dielectric is MKT, the German abbreviation for metallized polyester, with SH for self healing. Self healing is not a slogan either. The metallization is thin enough that a puncture in the film vaporises the electrode around the fault and clears it, so the capacitor survives events that would end a foil part. The carton gives HPF 25/085/21, the climatic category, which reads as a lower limit of minus 25 C, an upper limit of 85 C and 21 days of damp heat testing.
There is a real argument for buying an unused one rather than a pulled part. X2 capacitors sit directly across the mains and take every transient the supply delivers, so their capacitance falls and their losses climb over years in service. This one has taken none of that.
The carton carries VDE 565-1 and a row of national approval marks.
Questions about this part
What does class X2 actually mean?
It means the capacitor is qualified to sit line to line across the mains supply. Safety capacitors are classified by where they go and by what happens when they die. An X capacitor goes across the line, a Y capacitor goes from line to earth. X2 is the common subclass for equipment on ordinary domestic supplies, tested to survive a specified impulse and, crucially, built so that failure leaves it open circuit rather than short circuit.
Can I substitute an ordinary film capacitor of the same value and voltage?
No. This is the one substitution you must not make. An ordinary film capacitor may carry the same 2.2 uF and the same printed voltage and still be entirely unsuitable, because it is not built or tested to fail open. Across the mains, a capacitor that fails short is a direct fault path and a fire risk. If the original was X2, the replacement is X2.
Is a 250 V AC rating the same as 250 V DC?
No, and confusing the two is a common and expensive error. An AC rating accounts for continuous reversal, dielectric heating and the peak voltage, which for a 250 V AC sine is around 354 volts at the crest. A capacitor rated 250 V DC is not rated for 250 V AC. This one is rated in AC volts, which is what a mains part needs.
What does MKT self healing mean in practice?
MKT is metallized polyester: the electrode is a vanishingly thin metal layer evaporated straight onto the film rather than a separate foil. If the film punctures, the fault current vaporises the metallization immediately around the hole and isolates it, so the capacitor clears the defect and carries on with a fractionally lower capacitance. A foil capacitor has no such mechanism and the puncture becomes a permanent short.
Why buy new old stock rather than a used pull?
Because this is one of the few components where age in service genuinely matters. An X2 sits directly across the mains and absorbs every surge and transient the supply delivers, and each self healing event removes a little electrode. A capacitor pulled from equipment has an unknown history of exactly that. This one has been in a box since it was made and has cleared no faults at all.
What does HPF 25/085/21 mean?
It is the climatic category, a standard three field code. The first number is the lower category temperature in degrees Celsius below zero, so minus 25. The second is the upper category temperature, 85. The third is the number of days of damp heat testing, 21. It describes the environmental envelope the design was qualified against, not the everyday operating range.
What condition is this one in?
New old stock in its original carton, never fitted. The printing on the box is fully legible including the part number, the ratings and the approval marks, and the capacitor body inside is clean and unmarked with straight terminals. The photographs show the actual item and its box.