SCR Thyristor Module Selection Guide: Current Class, Voltage, Cooling and Model Verification

2. Current Class Helps Screen the Family — It Does Not Complete the Selection

The published current classes are useful for narrowing the candidate family.

For example, if a project has already established a required current class, the buyer can identify which published RITOKS family contains a corresponding class and then continue the verification process.

That does not mean:

required load current = same-number SCR module

or:

choose the nearest larger current class automatically.

Current rating is only one part of thyristor-module selection.

The exact device documentation may also contain blocking-voltage ratings, surge-current limits, temperature conditions and other model-specific parameters. Vishay’s current thyristor-module parametric catalogue, for example, separates current, blocking voltage, surge current, maximum junction temperature, dv/dt, package and circuit configuration as distinct fields.

For RITOKS modules, those external manufacturer values must never be transferred to MTC or MTA models.

4. Do Not Infer MTC or MTA Topology From the Family Name

This is one of the most important boundaries in the current SCR range.

The letters MTC and MTA should be treated as RITOKS product-family names unless an exact technical source establishes the internal circuit.

For Products 346 and 347, the current pages do not publish:

• number of SCR devices
• internal topology
• terminal polarity
• circuit diagram

For Product 348, the supplier table supports only:

two SCR devices

It does not establish how they are electrically connected.

Therefore, do not publish a general rule such as:

• MTC means [specific topology]
• MTA means [specific topology]

A future MTC-vs-MTA topology article should wait until verified circuit diagrams and datasheets are available.

6. Cooling Must Be Confirmed by Exact Variant

Cooling information also differs in completeness.

MTC 55A–200A

The exact cooling arrangement is not currently published.

MTC 250A–1500A

Water-cooled versions are mentioned for selected models only.

This does not mean every model in the family is water-cooled.

MTA 25A–1000A

Selected water-cooled versions are also mentioned.

Again, availability must be confirmed by exact model.

Power-semiconductor thermal management depends on the device, losses, package and operating environment; the Semikron Danfoss Application Manual treats semiconductor selection, operating conditions and thermal management as linked application-specific tasks rather than interchangeable fixed rules.

For an RITOKS inquiry, the safe wording is:

Cooling arrangement: confirm for exact model and project.

8. Gate Data Must Come From the Exact Datasheet

Gate triggering is an example of why model-specific documentation matters.

Infineon’s official thyristor triggering guidance treats gate-trigger data as device/datasheet-specific and notes that the actual trigger signal still depends on application needs.

That means this RITOKS selection guide should not invent or recommend:

• gate current
• gate voltage
• pulse width
• gate resistor
• firing-angle settings
• trigger waveform

for Products 346, 347 or 348.

Current RITOKS pages do not publish the required gate data.

Request the exact datasheet before designing the control circuit.

9. Surge, dv/dt and di/dt Are Also Model-Specific

Thyristor datasheets commonly specify dynamic and transient parameters separately from nominal current.

Official Infineon device documentation, for example, publishes parameters such as critical current-rise rate, blocking voltage, surge current, thermal resistance and junction temperature on exact device pages.

Those examples show why these parameters must be verified by exact device.

They are not RITOKS values.

The current RITOKS MTC/MTA pages do not publish enough evidence to provide:

• surge-current sizing
• dv/dt limits
• di/dt limits
• thermal-resistance values
• maximum junction temperature
• repetitive/non-repetitive current rules

Do not substitute another manufacturer’s numbers.

10. How to Use the Published Current Ranges

A conservative workflow is:

Step 1 — Start With the Project Requirement

Identify the electrical requirement already defined by the project.

Step 2 — Screen the Published Current Classes

Check which RITOKS family contains a relevant published class.

Step 3 — Confirm Voltage

Request the exact voltage rating/version.

Step 4 — Confirm Configuration

If topology or polarity matters, request the exact circuit and terminal diagram.

Step 5 — Confirm Cooling

Verify the cooling arrangement for the selected variant.

Step 6 — Confirm Mechanical Fit

Request package dimensions and mounting data.

Step 7 — Request Exact Datasheet

Confirm gate, surge, dv/dt, di/dt, temperature and other required electrical data from the selected model documentation.

Step 8 — RFQ

Quote the exact verified model and required documentation.

This workflow does not automatically select the SCR module.

13. Information to Include in an SCR Thyristor Module Inquiry

A useful inquiry can include:

• Application: [application]
• Required current class: [requirement]
• Required voltage: [requirement]
• Required circuit/configuration: [if known]
• Cooling requirement: [known requirement]
• Preferred family/model: [if known]
• Required dimensions/drawing: [if required]
• Required terminal/circuit diagram: [if required]
• Required datasheet/electrical data: [list]
• Required certification/test evidence: [if applicable]
• Quantity: [quantity]
• Destination: [country / region]
• Required delivery: [schedule]

If the electrical or mechanical requirement is not yet defined, mark it:

To be confirmed

rather than assuming a value from the family name.

Frequently Asked Questions

Need Help Narrowing an SCR Thyristor Module Family?

Start with the project requirements already defined:

• current class
• voltage requirement
• required circuit/configuration
• cooling
• package constraints
• documentation requirements
• quantity

Then screen the published MTC and MTA families and confirm the exact model before ordering.

• View Power Semiconductor Modules →
• View SCR Thyristor Modules →
• View MTC 55A–200A SCR Modules →
• View MTC 250A–1500A High-Current SCR Modules →
• View MTA 25A–1000A Dual-SCR Modules →