Disc-Type vs PCB-Type HV Bridge Rectifier: Which Should You Specify?
Updated: Aug 6
Transformer manufacturers, test-equipment builders, and ESP integrators asking us for a bridge rectifier almost always ask the same follow-up: disc-type or PCB-type? A lot of published guidance answers this on voltage class — disc for high voltage, PCB for low. That is not how the decision actually works, and it is not how we build.
Ameet Electro Systems (Nashik, Maharashtra) manufactures both constructions at 70 kV and 95 kV, at the same 1.4 A average DC output, in enclosures of near-identical footprint. The choice between them is not a voltage ceiling and not a size saving. It comes down to three things: the medium the assembly will operate in, whether you need to service it in the field, and how tightly it has to fit a repeatable production geometry.
What is the difference between a disc-type and a PCB-type HV bridge rectifier?
A disc-type bridge rectifier stacks individual epoxy-moulded HV diode discs into a clamped series string bolted to a copper bus bar. A PCB-type bridge rectifier mounts the diode string on a glass-fibre high-voltage insulating substrate, with copper bus bars carrying the terminal connections. Both produce high-voltage DC at the same ratings. They differ in how the insulation is achieved, and therefore in where each one can be installed and how it is maintained.
How disc-type construction works
In a disc-type assembly, individual HV diode discs are stacked in series and clamped to a tin-plated copper bus bar, with the number of discs set by the target voltage class. Each disc provides roughly 20–25 kV of reverse blocking voltage — our ARE20A disc is rated 22.5 kV VRRM — so a 70 kV assembly is a calculated stack, not a single component.
Two properties follow from that construction:
It runs in oil. Disc assemblies are rated for continuous operation immersed in transformer oil, which is what makes them the standard choice inside transformer test rigs and ESP transformer-rectifier (TR) sets. The ARE20A disc is specified for oil service.
It is field-serviceable. Because each disc is a discrete clamped element, a failed disc can be identified and replaced without discarding the assembly — which matters for equipment expected to stay in service for years between overhauls.
AES manufactures disc-type bridge rectifiers at 70 kV / 1400 mA (490 × 195 × 90 mm) and 95 kV (640 × 350 × 90 mm). Both terminate in M8 nut-bolt connections — AC input, output +Ve and output −Ve — on a tin-plated copper bus bar.
How PCB-type construction works
A PCB-type bridge rectifier mounts the diode string on a high-voltage insulating PCB substrate rather than a mechanical clamp stack. Our assemblies use a 2× PCB-sheet construction with copper bus bars at 30 × 6 mm and 25 × 8 mm, fixed with tin-plated M8 nut-bolts. The board provides both the mechanical structure and consistent dielectric spacing between diode elements.
The consequences here are different, and they are not about size:
The insulation is the board, not the air gap. PCB-type is specified where the assembly operates in air, with the substrate providing the primary dielectric — typically inside an enclosed HV power supply module rather than submerged in a transformer tank.
The geometry is repeatable. Every unit comes off the same board layout, so dimensional consistency across a production run is inherent rather than dependent on a clamping process. If you are integrating a rectifier stage into a series-built instrument or sub-assembly, that repeatability is usually the deciding factor.
AES manufactures PCB-type bridge rectifiers at 70 kV (1BR70P) and 95 kV (1BR95P). Both are vibration-tested by ETDC (Electronics Testing and Development Centre) before dispatch.
Disc-type vs PCB-type: the actual specifications
Confirmed figures from our datasheets, not general industry guidance:
Parameter | 70 kV disc-type | 70 kV PCB-type (1BR70P) | 95 kV disc-type | 95 kV PCB-type (1BR95P) |
Rated voltage | 70 kVP | 70 kV (VRRM 210 kV per diode) | 95 kVP | 95 kV (VRRM 290 kV per arm) |
Output current | 1400 mA | 1.4 A IDAV @ Tc 100 °C | 1000 or 1400 mA — specify on enquiry | 1.4 A IDAV @ Tc 100 °C |
Construction | Stacked epoxy-moulded diode discs on tin-plated Cu bus bar | 2× PCB-sheet assembly, Cu bus bars 30 × 6 mm and 25 × 8 mm | Stacked epoxy-moulded diode discs on tin-plated Cu bus bar | 2× PCB-sheet assembly, Cu bus bars 30 × 6 mm and 25 × 8 mm |
Dimensions | 490 × 195 × 90 mm | 490 × 214 mm | 640 × 350 × 90 mm | 640 × 350 mm |
Terminals | AC in, +Ve, −Ve — all M8 nut-bolt | AH (−Ve), AS1 (+Ve), AC × 2 — M8 | AC in, +Ve, −Ve — all M8 nut-bolt | AH (−Ve), AS1 (+Ve), AC × 2 — M8 |
Operating medium | Oil | Air | Oil | Air |
Field serviceability | Individual discs replaceable | Replaced as an assembly | Individual discs replaceable | Replaced as an assembly |
Applications | Dust precipitators, X-ray equipment | ESP, HV power supply | Dust precipitators, X-ray equipment | ESP, HV power supply |
Read the dimensions row carefully, because it is the row most buyers assume they already know: at 70 kV the two constructions differ by 19 mm on one axis, and at 95 kV the footprints are identical. Choosing PCB-type to save panel space is not a real trade-off in this range. Choose it because the assembly runs in air and you want repeatable geometry.
PCB-type datasheet figures in full. Both PCB assemblies are rated at 50 A IFSM for a 10 ms non-repetitive surge and specified over −40 to +125 °C. Reverse leakage is 1–5 µA at 25 °C, rising to 50–100 µA at 100 °C. The 1BR70P weighs 4.0 kg and accepts a supply of up to 120 kV AC RMS; the 1BR95P weighs 5.3 kg, accepts up to 160 kV AC RMS, and is rated to a maximum operating frequency of 5 kHz. Tell us the working voltage, output current and operating medium and we will send the full datasheet for whichever construction fits.
When to specify disc-type
Specify disc-type when:
The assembly will be immersed in transformer oil — transformer induced-voltage and no-load loss test rigs, ESP TR sets
The equipment will be serviced in the field across a long operating life, and you want a failed element replaceable rather than the whole assembly scrapped
You are supplying into an installed base already built around disc stacks and need mechanical and maintenance consistency with it
When to specify PCB-type
Specify PCB-type when:
The assembly operates in air, inside an enclosed HV power supply module or instrument
You need repeatable dimensional geometry across a production run — series-built test instruments, OEM sub-assemblies
The unit will be replaced rather than repaired at end of life, which is the normal service model for a sealed module
Both routes give you the same voltage class and the same current. Neither is the premium option.
Standards and insulation coordination
Both constructions are specified with insulation coordination in mind — ensuring clearance and creepage distances suit the working voltage and the operating environment, per IEC 60664. For rectifier assemblies feeding transformer test equipment, this sits alongside the standards the test equipment itself is built to, typically IEC 60076 and IS 2026.
Our bridge rectifiers are manufactured in-house at Satpur MIDC, Nashik — Maharashtra's established industrial corridor — and PCB-type assemblies are vibration-tested by ETDC before dispatch. Ameet Electro Systems is MSME UDYAM registered (UDYAM-MH-23-0235305) with export credentials (IEC 3116911487); GSTIN 27AHZPP6922A1ZY.
Frequently asked questions
Can a PCB-type bridge rectifier be used above 50 kV?
Yes. AES manufactures PCB-type bridge rectifiers at both 70 kV (1BR70P) and 95 kV (1BR95P), with VRRM ratings of 210 kV and 290 kV per arm respectively. Voltage class is not what separates the two constructions — operating medium and serviceability are.
Which construction is easier to repair in the field?
Disc-type. Each diode disc is a discrete clamped element, so a failed disc can usually be identified and replaced without rebuilding the assembly. PCB-type assemblies are replaced as a complete unit, which is the normal service model where they are used.
Can either construction be immersed in transformer oil?
Disc-type assemblies are rated for continuous operation in oil — the ARE20A diode disc used in the stacks is specified for oil service, and it is the construction we supply for transformer test rigs and ESP transformer-rectifier sets. PCB-type assemblies are specified for operation in air. If your application puts the rectifier inside a tank, specify disc-type; if you are unsure, send us the installation detail and operating temperature and we will confirm the right construction before you order.
Does disc-type cost more than PCB-type at the same rating?
Cost depends on voltage, current rating, and quantity — there is no fixed rule that one construction is cheaper. Send us your specification and we will quote against it.
What is the lead time for a 70 kV or 95 kV bridge rectifier?
Standard lead time is 2–4 weeks from confirmed order. Export shipments are despatched FOB Nhava Sheva (JNPT, Navi Mumbai) with commercial invoice, packing list, and Certificate of Origin (India).
Are AES bridge rectifiers tested before dispatch?
Yes. PCB-type bridge rectifiers are vibration-tested by ETDC. Every assembly is manufactured under strict quality control in-house at our Nashik facility.
Request a datasheet
Tell us four things and the construction usually selects itself:
Working voltage and required output current
Operating medium — oil or air
Space envelope
Whether the assembly must be field-serviceable
Email: ameetsys@yahoo.com Contact Form →
We respond within one working day with a datasheet and a recommended configuration.
Comments