Solid-State Relays vs Electromechanical Relays
How solid-state relays and electromechanical relays work, how they fail, and how to choose between them for a control panel.
3JIndustry · Guides techniques
Guides techniques et actualités
Replacing a Legacy Variable Frequency Drive: What to Check
A checklist for replacing an older variable frequency drive with an identical used spare or a current-generation model, beyond the HP or kW rating.
Overload Relays: Thermal vs Electronic and Trip Classes 10, 20, 30
How thermal and electronic overload relays protect motors, what trip classes 10, 20 and 30 mean, and how to set and reset a relay correctly.
NPN vs PNP Sensors: Sinking, Sourcing and How to Wire Them
What NPN and PNP outputs mean, how they match sinking and sourcing input cards, and how to wire 3-wire and 2-wire DC sensors.
Miniature Circuit Breaker Trip Curves B, C and D Explained
B, C and D trip curves set the instantaneous trip range of a miniature circuit breaker. Learn the IEC 60898-1 ranges, see worked examples and choose...
Manual Motor Starters (MPCB): How They Work and How to Set Them
How manual motor starters (MPCBs) such as PKZM, GV2 and 140M combine overload and short-circuit protection, and how to set them to the motor full-load current.
Legacy PLC Obsolescence: Keep It Running or Migrate?
A practical way to decide whether to keep a legacy PLC running or migrate it, with a spare-parts, backup and phased-migration plan.
How to Read Industrial Part Numbers and Nameplates Before You Order
Learn the difference between catalog and serial numbers, why series letters and voltage codes matter, and how to photograph a nameplate so you order the right...
Contactor Coil Voltages and Coil Codes: How to Get the Right One
How contactor coils differ (AC or DC, 50 or 60 Hz, electronic) and how to read coil markings and codes so the replacement closes reliably.
Buying Used and Legacy Industrial Parts: A Practical Checklist
A practical checklist for buying used and legacy industrial parts: part number and series, coil voltage, firmware, photos, condition notes, warranty, lead time and cross-border shipping.
Réseaux d'alimentation électrique et types de charges en Amérique du Nord
A practical overview of North American supply systems, from 120/240 V split phase to 600Y/347 V in Canada, how loads connect, and why slash ratings matter.
Fonctionnement : alimentations électriques
How industrial DC power supplies work, why 24 VDC is the standard control voltage, and how to size and replace a supply with the right margin.
