Bad Electrical Panel. A Rare Speed Commander Appears! A Danish 4kW Motor Drive

I got hold of two electrical panels with a bad wiring job, worst documentation and completely out of code (racing fast for illegal). The did …

Teardown of a 5 kVA / 4 kW Eaton EX5RT UPS System

Teardown of a Eaton EX RT 5 kVA UPS model. The topology is a on-line double conversion with PFC (Power Factor Correction) system for a …

3 kW Yaskawa Servo Motor Teardown – Isolation, Day 38

I scavenged a old 4 ton stone polisher machine for the best components and got off with a 3 kW AC server motor + drive, …

3-Phase IGBT Module Teardown – Fuji 7MBP50RA120 From 3 kW Omron Servo Drive – Isolation, Day 36

I scavenged a old 4 ton stone polisher machine for the best components and got off with a 3 kW AC server motor + drive, …

Omron/Yaskawa 3 kW AC Servo Drive Teardown – Isolation, Day 34

I scavenged a old 4 ton stone polisher machine for the best components and got off with a 3 kW AC server motor + drive, …

3 kW AC Servo Drive From a 4 Ton Stone Polisher – Isolation, Day 32

I scavenged a old 4 ton stone polisher machine for the best components and got off with a 3 kW AC server motor + drive, …

10 kVA Kjellberg Plasma Cutter CUTi 31 Teardown

A teardown of a Kjellberg CUTi 31 Plasma Cutter with a power rating of 10 kVA. Made for cutting in 25-30 mm steel. Connecting voltage …

ABB TRIO 20 kW Solar Inverter – Unboxing and Teardown

Three-phase string inverter, 20000Wac, 2 MPPT, 4 DC inputs for each MPPT, RS485 communication interface, IP65 (NEMA4x) environmental protection degree, integrated DC and AC disconnect …

Siemens Polyphos 30, X-RAY Inverter and Control Panel Teardown (Part 3 of 3)

Teardown of the Siemens Polyphos 30 X-ray systems control panel including computer, safety functions, HMI and high voltage inverter circuit.

750W Victron Solar Project – Power wall and 8 days performance – Part 3

In part 3 I test the setup with all 3 panels connected and look at the performance over the last 8 days. It all consists …

Unboxing a Chinese 1800 Watt Induction heater

I finally got around to get the IH out of the box and repair it, here is part 1 of a series of videos on …

Snubber capacitor calculator

Here you can calculate the snubber capacitance that is needed to keep transient voltages below the maximum allowed value. Stray inductance is the inductance in the primary circuit of the inverter. If the stray inductance is not known, the two estimates can be used, high estimate for cable/wire primaries or long distances. Low estimate for copper busbar and short distances.

Switch between the input fields to automatically calculate the values.

Stray inductance nH
Peak current A
Max transient voltage V
DC bus voltage V
Results
Snubber capacitance uF
High inductance estimate uF
Low inductance estimate uF

Formulas used

Calculated snubber capacitance = Stray inductance * Peak current^2 / (maximum allowed transient voltage – DC bus voltage)^2

Snubber capacitance is given in Farad, stray indutance is given in Henry and voltage in Volt.

Estimated high inductance snubber capacitance = Peak current / 100

Estimated low inductance snubber capacitance = (Peak current / 100) * 0.5

Teardown video of Eaton PowerWare 30 kVA UPS

Here is a video from taking apart 3 UPS units from Eaton PowerWare, these are 30 kVA units that was previously described in pictures and …