Semikron SKKT162/16E — SEMIPACK®2 Dual Series Thyristor Module | 1600V / 156A | New Genuine

If you're looking at the SKKT162/16E, there's a good chance something in a DC motor drive, a temperature controller, or an industrial soft starter has failed and needs a direct replacement. This is one of Semikron's established SEMIPACK 2 format dual thyristor modules — a workhorse part that shows up in equipment built across several decades of industrial power electronics. The combination of a 1600V voltage rating and 156A average on-state current (250A RMS) positions it squarely in the mid-to-high current range for controlled rectifier applications.

✅ Genuine Semikron. New in original packaging. UL Recognized (File No. E63532). RoHS compliant.

Catalog Number Decoded — SKKT162/16E

Understanding Semikron's part numbering on SEMIPACK modules is useful when cross-referencing, selecting alternatives, or verifying you have the correct voltage class:

SK — Semikron manufacturer prefix, present on virtually all Semikron discrete and module parts.

KT — Circuit topology code. KT designates a dual thyristor (SCR) module in series connection — two thyristors sharing a common terminal (typically a common cathode-anode node), configured for use in anti-parallel or series circuit arrangements.

162 — Current class identifier within the SEMIPACK 2 housing. The 162 designation corresponds to the 156A average on-state current rating (IT(AV) at 85°C case temperature) and 250A RMS. This is a fixed current class for this housing format; other SEMIPACK 2 thyristor modules at the same current class will share this number.

16 — Voltage class in hundreds of volts: 16 × 100 = 1600V. This applies to both VDRM (peak repetitive off-state voltage) and VRRM (peak repetitive reverse voltage). The VRSM (non-repetitive peak) is rated at 1700V.

E — Package variant designation indicating the standard SEMIPACK 2 (case A21) format with screw-terminal power connections. The E suffix is standard across the SKKT162 voltage range (08E through 18E).

The SKKT162 series spans voltage classes from 800V (SKKT162/08E) through 1800V (SKKT162/18E). The /16E is one of the most commonly stocked variants because 1600V provides adequate derating margin for 690V AC three-phase rectifier input (which presents approximately 970V peak line-to-line voltage), leaving roughly 65% voltage utilization — within generally accepted design practice for industrial SCR circuits.

Technical Specifications

Parameter	Symbol	Value
Part Number	—	SKKT162/16E
Module Type	—	Dual thyristor (SCR), series connected
Package	—	SEMIPACK 2 (Case A21)
Number of Pins	—	7
Repetitive Peak Off-State Voltage	VDRM	1600V
Repetitive Peak Reverse Voltage	VRRM	1600V
Non-Repetitive Peak Reverse Voltage	VRSM	1700V
Average On-State Current (per SCR)	IT(AV)	156A (at TC = 85°C)
RMS On-State Current	IT(RMS)	250A
Peak Non-Repetitive Surge Current	ITSM	5.4kA (10ms, 125°C)
Gate Trigger Current (max)	IGT	150mA
Gate Trigger Voltage (max)	VGT	2V
Holding Current (max)	IH	400mA
Max Junction Temperature	Tj(max)	125°C
Isolation Voltage	Ui	3000V AC / 1min
SCR Configuration	—	Series connected — dual SCR with aux cathode
Baseplate	—	Aluminum oxide ceramic isolated metal
Joint Technology	—	Hard soldered
Certifications	—	UL Recognized, File No. E63532
RoHS	—	Compliant

Circuit Configuration — What "Dual Series Thyristor" Actually Means

The SKKT162/16E contains two thyristors (SCRs) in a single package, connected in series with a shared intermediate terminal. The seven-pin layout reflects this: main power terminals labeled 1, 2, and 3 (where terminal 2 is the common anode-cathode node between the two devices), plus individual gate and auxiliary cathode terminals for each thyristor — K1, G1, K2, G2.

This configuration is commonly used to build anti-parallel thyristor pairs for AC power control when two SKKT modules are used together. A single SKKT162/16E can also serve as one leg of a three-phase bridge rectifier, where each of its two thyristors handles one phase-to-DC bus switching event per cycle.

The auxiliary cathode terminals (K1, K2) are separate from the main cathode current path — they're low-current terminals intended for gate drive circuit reference. Using these rather than the main power terminal as gate drive reference prevents gate circuit interference from the main current commutation, which matters at high current levels where di/dt effects on shared ground paths can cause false triggering.

Baseplate and Thermal Design

One of the consistent engineering strengths of Semikron's SEMIPACK series is the thermal interface design. The SKKT162/16E uses an aluminum oxide (Al₂O₃) ceramic isolated metal baseplate — a construction that simultaneously provides:

Electrical isolation between the silicon junction and the heatsink (rated at 3000V AC for 1 minute), eliminating the need for external isolating pads in most installations
High thermal conductivity relative to plastic encapsulation, enabling efficient heat transfer to the heatsink
Mechanical stability that survives the clamping forces required for good thermal contact with the heatsink surface

The hard soldered joints throughout the internal assembly are Semikron's deliberate choice over alternatives like pressure contact or conductive adhesive. Hard solder maintains consistent electrical and thermal contact through thermal cycling — critical in applications where the module sees repeated load cycles (motor starts, temperature cycling in furnace control), which would progressively degrade softer joint technologies.

When mounting to a heatsink, thermal interface material (Wärmeleitpaste / thermal grease or phase-change pad) between the module baseplate and heatsink surface is required to fill microscopic surface irregularities. Semikron's published mounting guidance for SEMIPACK 2 modules specifies the mounting screw torque and interface material requirements in the SEMIPACK application note series.

Typical Applications

Semikron's own documentation identifies the primary application domains for this module as DC motor control for machine tools, temperature control for ovens and chemical processes, and professional light dimming for studios and theaters. In practice, the SKKT162/16E appears across a broader range of controlled power applications wherever a mid-to-high current SCR bridge is needed:

DC Motor Drives — Controlled rectifier drives for separately-excited DC motors (field and armature control) in machine tools, rolling mills, paper machines, and winding equipment. The module typically operates in a three-phase fully-controlled bridge (six-pulse) where six thyristors — from three SKKT modules — rectify the AC supply into variable-voltage DC. At 690V AC three-phase input, the 1600V rating provides standard derating margin.

Temperature and Process Control — Phase-angle controlled heater systems for industrial furnaces, kilns, glass tempering equipment, and chemical reactors. SCR power controllers in this service see millions of firing cycles over years of operation; the hard-soldered construction's resistance to thermal fatigue is directly relevant here.

Soft Starters — AC motor soft starters use thyristors to ramp motor voltage during acceleration, reducing mechanical shock and inrush current. At 156A average current, the SKKT162/16E suits motors in the 55–110kW range depending on soft starter topology and duty cycle.

Welding Equipment — Resistance welding power supplies (spot and seam welding) that use controlled rectification to deliver precisely timed current pulses. The 5.4kA surge rating matters in this application — welding creates high-current transients that the module must withstand without damage.

The SKKT162/16E Voltage Class — Selecting the Right Variant

The SKKT162 series is available in five voltage classes. Choosing the right one involves a simple voltage utilization calculation:

Part Number	VDRM/VRRM	Typical AC Input	Application
SKKT162/08E	800V	Up to 230V AC single-phase / 133V AC 3-phase	Low-voltage DC drives, 240V systems
SKKT162/12E	1200V	Up to 415V AC 3-phase	380–415V AC industrial systems
SKKT162/14E	1400V	Up to 500V AC 3-phase	500V systems with margin
SKKT162/16E	1600V	Up to 690V AC 3-phase	Standard European 690V drives, furnaces
SKKT162/18E	1800V	Up to 690V AC with extra margin	High-reliability, demanding environments

A useful rule of thumb for three-phase applications: multiply line-to-line AC voltage by √2 × √3 / √3 = √2 to get peak line-to-line voltage. For 690V AC: 690 × 1.414 ≈ 976V peak. With the 1600V VDRM, utilization is approximately 61% — standard conservative practice for industrial thyristor circuits where line transients and commutation overvoltages occur.

❓ FAQ — Semikron SKKT162/16E

Q1: What does the "dual series" configuration mean, and how are the two thyristors internally connected?

The SKKT162/16E contains two discrete thyristors mounted on a shared baseplate, connected in series with one shared intermediate terminal (terminal 2) that serves as the cathode of the first thyristor and the anode of the second. Each thyristor has its own gate terminal (G1, G2) and auxiliary cathode terminal (K1, K2) for the gate drive circuit. This arrangement allows each thyristor to be triggered independently. In a three-phase controlled bridge rectifier, two SKKT modules are used per phase leg (or one SKKT per phase with each thyristor handling a different half-wave event). The auxiliary cathode pins provide a clean reference for gate drive circuits, isolated from the main current path — important at high currents where voltage drops in shared ground conductors can interfere with gate triggering.

Q2: What is the difference between the SKKT162/16E and SKKT162/18E — is the extra 200V worth it?

Both modules share the same physical SEMIPACK 2 package and identical current ratings (156A IT(AV), 250A RMS). The difference is voltage headroom: the /16E is rated at 1600V VDRM/VRRM (1700V VRSM), while the /18E is rated at 1800V VDRM/VRRM. For 690V AC three-phase applications where line transients are well-controlled and upstream filtering is present, the /16E provides standard engineering margin. The /18E is chosen when the application sees frequent line transients, lacks adequate snubber protection, or when the designer prefers extra voltage derating for reliability in demanding environments (outdoor installations, poor power quality sites, offshore equipment). Replacing a failed /16E with an /18E is electrically safe — the higher voltage rating does not affect triggering behavior, on-state characteristics, or current ratings. The reverse is not true: do not substitute a /14E or /12E for a /16E in a 690V application.

Q3: What heatsink and thermal interface material does this module require?

The SKKT162/16E does not include a heatsink — it must be mounted to a separate heatsink appropriate for the application's thermal requirements. The aluminum oxide ceramic baseplate provides electrical isolation (3000V AC), so no additional isolating pad is typically needed between module and heatsink. However, thermal interface material (thermal grease or phase-change pad) is required between the flat module baseplate and heatsink surface to fill surface irregularities and maintain low thermal resistance. Semikron's SEMIPACK application notes specify acceptable interface materials and mounting torque values. Semikron offers compatible heatsinks in the SKxx series; third-party heatsinks with matching hole patterns for the SEMIPACK 2 footprint are also widely available. For the application's continuous operation, calculate the required heatsink thermal resistance from the junction temperature limit (125°C max), the expected power dissipation, and the maximum ambient temperature.

Q4: Can the SKKT162/16E be used as a direct replacement for older non-E suffix Semikron modules?

The "E" suffix in Semikron's SEMIPACK naming indicates the standard current-generation plastic-overmolded housing variant. Earlier production of similar modules may have used slightly different suffix conventions, but the electrical characteristics and SEMIPACK 2 mounting footprint are consistent. When replacing a failed module, verify three things: (1) the housing footprint matches (SEMIPACK 2 / Case A21), (2) the voltage class is equal or higher, and (3) the current rating is equal or higher. Cross-referencing by circuit topology (dual SCR, series connected) and terminal count (7-pin) helps confirm electrical compatibility. Modules from other manufacturers in the SEMIPACK 2 standard housing (Infineon, Vishay, ABB) with matching or better ratings can also serve as cross-references — the SEMIPACK 2 format is an industry-standard package with consistent mechanical dimensions across manufacturers.

Q5: What are the gate drive requirements for the SKKT162/16E?

Each thyristor requires a gate trigger current of up to 150mA maximum (IGT) at a gate trigger voltage of up to 2V maximum (VGT) to ensure reliable turn-on across the full temperature range. Practical gate drive circuits for industrial SCR modules typically deliver gate pulse currents of 0.5–1A for 10–20 microseconds to ensure reliable triggering regardless of load conditions and temperature variations. Gate drive isolation is standard practice — pulse transformers or optocoupler-based gate drive circuits isolate the control electronics from the high-voltage power circuit. The auxiliary cathode terminals (K1, K2) should be used as the gate drive reference rather than the main power cathode terminals to avoid interference from main circuit di/dt. Holding current maximum is 400mA, meaning the anode current must stay above this level after gate pulse removal to keep the thyristor latched — a factor to consider in light-load conditions.

Q6: What is the significance of the 5.4kA surge current rating?

The ITSM rating — 5.4kA for 10ms at 125°C junction temperature — describes the maximum peak current the device can withstand in a single non-repetitive event without damage. This rating is relevant in two scenarios: fault current during a downstream short-circuit (before the upstream fuse or breaker operates), and inrush current events in applications like transformer energization or capacitor charging. For protection coordination, the I²t value implied by this surge rating must be matched to semiconductor fuses — standard industrial fuses (gG/gL types) have insufficient I²t selectivity and will destroy the module before clearing the fault. Semiconductor-rated fuses (aR or gR class, sometimes labeled "ultra-rapid" or "semiconductor protection") are specified for thyristor module protection because they clear the fault current within the module's surge current withstand capability.

Q7: Is the SKKT162/16E still in production, and what is the lead time for new stock?

As of the current date, the SKKT162/16E remains an active Semikron part (now under Semikron Danfoss following the 2022 merger between Semikron and Danfoss' power electronics division). Major distributors including Newark/Farnell (part no. 01H8025) and TME (part no. 07894130) stock it as a standard item. Lead times vary by distributor; Newark lists same-day shipping for in-stock quantities. The SEMIPACK 2 format has been a stable industry standard for decades with no announced discontinuation. When sourcing replacements for older equipment, verify the module is from an authorized distributor or traceable-source industrial supplier — counterfeit SEMIPACK modules exist in the grey market and may lack the hard-soldered construction, proper ceramic isolation, or silicon quality that makes the genuine Semikron part reliable in continuous industrial service.

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