EI48 Potted PCB Mount Transformer, 220 V AC to 12 V AC, 10 VA, Epoxy Sealed, Through-Hole Pins, 50.7 x 38.3 x 43 mm
A potted EI48 transformer for equipment that needs an isolated 12 V AC rail from a 220 V AC supply and wants the part soldered straight into the board. The winding sits inside a blue flame-retardant case and is cast in epoxy, so the assembly is sealed against moisture and dust and held rigid against vibration, while four corner lugs take screws if the board also needs a mechanical fix. It is the familiar shape of a small chassis transformer, reduced to a through-hole footprint.
- 220 V AC primary to 12 V AC secondary, rated 10 VA, series quoted from 1 W to 12 W.
- Fully potted winding in black epoxy, sealed against moisture and dust.
- Blue flame-retardant case with a stepped lid; rating label on the front face.
- PCB through-hole pins plus four moulded corner lugs with screw holes.
- Outline 50.7 mm by 38.3 mm by 43 mm, pin rows 28.8 mm apart.
- Class B insulation, 40 °C ambient according to the label.
- CE, Class II and cRUus marks shown, with no certificate number supplied.
1. Product Name
EI48 potted transformer wound for a 220 V AC primary and a 12 V AC secondary at 10 VA, in a through-hole package. The designation on the label carries all four facts in one string, EI48-10W/VA 220V/12V, so the ordering description can be built from the series, the rating and the voltage pair without a separate catalogue number.
A separate panel quotes the series across 1 W to 12 W, so the outline is shared and the winding is what changes. Another rating inside that range keeps the footprint and the mounting; the winding, the pinout and the label move with the order. Confirm the rating in writing, because the documents supplied mix a 5 VA build into the same drawing.
2. Construction & Encapsulation
The core is an EI48 lamination stack, wound on a bobbin and terminated on pins that pass through the base moulding. The finished winding is dropped into the blue case and the case is filled with epoxy, so the coil, the core and the pin roots end up in one solid block. The lid is a separate moulding stepped into the body, which leaves the seam above the potting line rather than at the base where the pins exit.
The case is a blue moulding described as flame retardant, with a stepped lid and four corner pads moulded into the base. Each pad carries a screw hole for a mechanical fix, which is what lets the part survive handling and vibration in equipment that is moved or shipped assembled. The rating label is applied to the front face, so the model, the voltages and the pin numbers stay readable after the board is populated.
The potting carries the electrical safety argument on this page. A void-free fill removes the air path around the winding, which lengthens the creepage path from primary to secondary along the surface, and it locks the laminations so they cannot buzz. It also closes the case to moisture and dust. Not given: the compound, its temperature index, or the voltage the fill was tested at.
3. Termination & Mounting
Termination is by straight pins on a through-hole pattern, with the labels assigning the primary to pins 1-6 and the secondary to pins 7-12. Around the pins, four corner lugs with screw holes give a second, mechanical attachment to the board or to a bracket, which is unusual on a part this small and is the reason the corner pads are moulded as part of the base.
4. Dimensions
The outline is dimensioned on a dedicated sheet: 50.7 mm across the pin face, 38.3 mm front to back, 43 mm from the seating plane to the top of the stepped lid, with the pin rows 28.8 mm apart and a 6 x 4.2 mm callout across a row.
5. Feature
Sealed against the environment. Epoxy casting keeps moisture, dust and condensation off the coil, so the part does not need a sealed enclosure around it.
Through-hole termination. Straight pins are placed and soldered with the rest of the board, removing a wiring step and a connector from the assembly.
Corner screw lugs. Four moulded lugs take the mechanical load off the solder joints where the board sees vibration.
Small footprint at 10 VA. 50.7 mm by 38.3 mm by 43 mm keeps a 10 VA linear supply on the control board instead of beside it.
Class II construction shown. The double square is marked on the material, the construction that does not rely on an earth connection for basic insulation.
Stepped lid. The lid steps into the body, so the seam sits above the potting line and away from the pin exits.
Rating on the face. Model, input, output and pin numbers are printed on the label, so the part is identifiable after assembly.
6. Advantage
No separate enclosure. Case and potting are part of the part, so a design adds no box, bracket or conformal coat.
Fewer assembly steps. Pins and corner screws replace flying leads, a terminal block and the labour of dressing a harness.
Stable in vibration. A solid epoxy block has no free laminations or loose layers, so it does not rattle or fret its insulation.
Predictable handling. One smooth moulding reaches the line, with no exposed copper, tape edge or core corner to damage.
Shared outline across ratings. One footprint covers 1 W to 12 W, so a product family keeps the same cut-out and screw positions.
Serviceable. The part desolders and lifts out without cutting a harness, which suits a long field life.
7. Specifications
Values are transcribed from the supplier artwork. Where it is silent the cell reads Not stated; where it contradicts itself the contradiction is named rather than resolved.
7.1 Summary
| Item | Specification | Note |
|---|---|---|
| Product | EI48 potted PCB mount transformer | Through-hole, epoxy filled |
| Model | EI48-10W/VA 220V/12V | Series, rating and voltage pair in one string |
| Rated power | 10 VA | Series quoted from 1 W to 12 W |
| Primary | 220 V AC | Label assigns pins 1-6 |
| Secondary | 12 V AC | Label assigns pins 7-12 |
| Frequency | 50 Hz or 60 Hz | Taken from the 5 VA label on the drawing |
| Insulation | Class B | Label also reads ta 40 °C |
| Case | Blue flame-retardant moulding, stepped lid | Material grade not stated |
| Encapsulation | Black epoxy, fully potted | Compound not stated |
| Mounting | PCB through-hole plus 4 corner lugs | Hole diameter not stated |
| Outline | 50.7 mm x 38.3 mm x 43 mm | Height excludes the pins |
| Weight | Not stated | Confirm on the order |
7.2 Electrical
| Parameter | Value | Note |
|---|---|---|
| Rated power | 10 VA | The rating printed on the 10 VA label |
| Power range | 1 W to 12 W | Series panel in the same material |
| Primary | 220 V AC | Pins 1-6 per label |
| Secondary | 12 V AC | Pins 7-12 per label |
| Frequency | 50 Hz or 60 Hz | From the 5 VA label; the 10 VA label omits it |
| Insulation class | Class B | Label reads ta 40 °C / B |
| Rated ambient | 40 °C | Label reads ta 40 °C |
| No load current | Not stated | Ask for it with the winding data |
| Voltage regulation | Not stated | Ask for it at a stated load |
| Winding resistance | Not stated | Per winding, at a stated temperature |
| Dielectric strength | Not stated | Every unit is stated to be high-pot tested, no voltage given |
7.3 Mechanical
| Item | Specification | Note |
|---|---|---|
| Width across the pin face | 50.7 mm | Dimension sheet |
| Depth, front to back | 38.3 mm | Dimension sheet |
| Overall height | 43 mm | To the top of the stepped lid, pins excluded |
| Pin row spacing | 28.8 mm | Between the two rows |
| Pin pitch | 4.2 mm | Callout reads 6 x 4.2 mm across the row |
| Footprint | 50.7 mm x 38.3 mm | Case outline, lugs included |
| Corner lugs | 4, one per corner | Screw holes, diameter not stated |
| Case material | Flame-retardant moulding, blue | Grade and flammability class not stated |
| Potting | Black epoxy, fully filled | Compound not stated |
| Weight | Not stated | Confirm on the order |
| Pin length | Not stated | Needed to work out the stand-off below the board |
7.4 Pinout
| Item | Specification | Note |
|---|---|---|
| Pin type | Straight, through-hole, solder | Diameter and length not stated |
| Positions drawn | 10, numbered 1-5 and 10-6 | Two rows of five on the dimension sheet |
| Positions referenced by the label | 12, pins 1-6 and 7-12 | Conflict with the drawing |
| Positions visible in the photographs | 4 | Conflict with both |
| Primary assignment | Pins 1-6 | Per label, not verified against the winding |
| Secondary assignment | Pins 7-12 | Per label, not verified against the winding |
| Polarity | Not stated | No dot or start marking shown |
| Pin plating | Not stated | Ask for it with the drawing |
7.5 Quality and compliance
| Item | Statement | Note |
|---|---|---|
| High-pot | Every unit stated to be high-pot and insulation tested | No test voltage or duration given |
| Insulation resistance | Not stated | Ask for the value and the test voltage |
| RoHS | A RoHS statement appears in the material | No certificate number or test report supplied |
| Marks shown | CE, Class II double square, cRUus | No certificate number or issuing body |
| Position taken here | No compliance claim is made | Ask for the certificate your market needs |
| Traceability | Serial number printed on the label | Format not explained |
8. Application
The uses below are general application context for a potted 10 VA mains transformer, not claims taken from the source.
Home appliances. Household devices that need 12 V from the mains, where the sealed case suits steam and cleaning.
Industrial control. Control boards and panels that want the supply soldered on rather than wired to a separate block.
Security equipment. Cameras and access control, where a sealed part avoids corrosion in damp cabinets.
Smart home systems. Panels, hubs and gateways that need an isolated rail on a compact, low profile board.
LED power supply. Strips and modules on a 12 V AC rail, where the driver accepts AC rather than rectified DC.
Audio and communication. Equipment where a low hum supply matters, which is what the solid potting is there to give.
9. Ordering
Quote against the rating and the pinout. A useful enquiry gives the power rating you need inside the 1 W to 12 W range, the primary and secondary voltages, the pinout or the footprint you are laying out to, whether the corner screws will be used, and the quantity per order and per delivery. With those we confirm the winding, the pin assignment and the price.
On compliance: the material shows CE, a Class II double-square and a cRUus mark, and carries a RoHS statement, but no certificate number, issuing body or test report comes with it, so no compliance claim is made here. If your market needs a declaration, ask for the certificate for the specific standard. A logo panel on its own is not evidence of certification.
Brand / manufacturer: ZXY, Shenzhen Zhixiangyuan Electronics Co., Ltd. http://www.zxycoil.com