How to Select the Right MCB: Complete Checklist
A seven-step decision path for sizing an MCB correctly, from load current and cable coordination to tripping curve, breaking capacity, poles, standard, and derating.
8 min read
Technical
Technical for buyers and panel builders
Guides and notes on industrial electrical and automation parts: selection, wiring, settings and ordering.
- Articles
- 542
RCD Selectivity: S-Type vs Instantaneous Discrimination
How S-type selective RCDs coordinate with downstream instantaneous devices using the 2x current ratio and time-delay rule from IEC 60947-2 and IEC 61008-1.
9 min read
European vs Chinese MCCB Brands: ABB, Schneider, Siemens vs Chint, LS
A grounded comparison of European MCCB brands (ABB, Schneider Electric, Siemens) against Chinese brands (Chint, LS Electric, Delixi) on breaking-capacity testing, certification, trip-unit sophistication, price, and spare-parts availability.
11 min read
Overvoltage and Undervoltage Monitoring Relays
How overvoltage and undervoltage monitoring relays use threshold, hysteresis, and trip delay to protect motors and panels from voltage faults.
9 min read
VFD Communication: Modbus, PROFINET and EtherNet/IP
How VFDs exchange data with a PLC over Modbus RTU, PROFINET, EtherNet/IP, and EtherCAT, and how to pick the right protocol for the plant network.
9 min read
Class 10 vs Class 20 vs Class 30: Matching Trip Class to Start Time
How to match an overload relay's IEC 60947-4-1 trip class (10, 10A, 20, 30) to a motor's real run-up time instead of guessing.
11 min read
Soft Stop, Pump Control and Braking on a Soft Starter
How a soft starter's soft-stop function paces motor deceleration to prevent pump check-valve slam, and why that is not the same as active braking.
10 min read
Magnetic-Only MPCB with a Separate Overload Relay
How a magnetic-only MPCB pairs with a separate overload relay: FLC setting, trip class, and Type 2 coordination.
8 min read
Main Parts of an MCB and What Each Does
The six functional parts of an MCB - lever, contacts, thermal strip, magnetic trip coil, arc chute, and trip-free mechanism - and how they divide overload versus short-circuit protection.
10 min read
RCD Trip Time and IEC 61008 Test Requirements
IEC 61008-1 sets exact maximum break times for RCCBs at IΔn, 2×IΔn and 5×IΔn, plus a slower band for S-type selective devices, and this covers what the numbers mean and...
8 min read
Best MCCB Brands for Industrial Panels Ranked
A field-grounded ranking of ABB Tmax XT, Schneider ComPact NSX, and Siemens Sentron 3VA MCCBs for industrial panels, weighing breaking capacity, trip-unit ecosystem, and real-world availability.
11 min read
Three-Phase Voltage Monitoring Relays: Sequence & Loss
How three-phase voltage monitoring relays detect phase sequence errors, phase loss, voltage asymmetry, and over/undervoltage before motor damage.
8 min read
VFD Enclosure Ratings: IP20, IP55 and Cabinet Cooling
IP20, IP55 and IP66 enclosure ratings for VFDs, NEMA/UL equivalents, and how to size cabinet cooling so the drive doesn't overheat or corrode.
8 min read
Overload Relay Trip Classes 10A, 10, 20 and 30 Explained
IEC 60947-4-1 trip classes 10A, 10, 20, and 30 define how fast a thermal overload relay must trip at 7.2x its current setting, and picking the right one keeps nuisance...
9 min read
Soft Starter Heat Dissipation and Enclosure Cooling
SCR conduction loss, the bypass contactor's role, AC-53a/AC-53b duty sizing, and enclosure cooling options for soft starters.
9 min read
MPCB Plus Contactor: Building a Motor Starter
How an MPCB and a contactor combine into a compliant motor starter, covering the two build types, contactor sizing, Type 1/2 coordination, and mounting.
10 min read
MCB vs Fuse: Which Protects Better
A technical comparison of MCB and fuse protection covering trip mechanism, breaking capacity, discrimination behavior, and total cost of ownership.
9 min read
Type A vs Type B RCD: Which for VFD, EV and Solar
Type A RCDs resolve AC and pulsating DC, while Type B is required wherever a fault can produce smooth DC, covering three-phase VFDs, most EV chargers, and transformerless solar inverters.
9 min read
Ekip vs Micrologic vs ETU: MCCB Electronic Trip Units Compared
A side-by-side technical comparison of ABB Ekip, Schneider Micrologic, and Siemens ETU electronic trip units on protection functions, setting method, metering, communication, field-swappability, and ergonomics.
11 min read
Phase Sequence and Phase Failure Monitoring Relays Explained
How phase sequence and phase failure monitoring relays detect wrong rotation, catch lost phases, and prevent single-phasing motor damage in three-phase panels.
8 min read
VFD Overload: Normal Duty vs Heavy Duty Ratings
A field guide to VFD Normal Duty and Heavy Duty overload current ratings — what the percentages mean, why the same frame gives less kW in HD, and how to...
9 min read
How a Bimetallic Overload Relay Trips: The Differential Principle
How the differential trip bar in a bimetallic overload relay senses phase imbalance and drives the inverse-time trip curve.
10 min read
Soft Starter Motor Protection: Overload, Phase Loss, Stall
How a soft starter's I2t thermal model, phase-loss, phase-sequence, locked-rotor/stall, shorted-SCR and undercurrent functions protect the motor and starter.
9 min read
MPCB Type 1 vs Type 2 Coordination Explained
IEC 60947-4-1 Type 1 permits component damage after a fault while Type 2 limits it to separable contact welding, and the choice comes down to acceptable downtime on that branch.
8 min read
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