Guides

Quick answer: A CPS (Control & Protective Switching device) is an all-in-one motor starter that combines what normally takes three separate devices — a contactor, an overload relay, and short-circuit protection — into a single compact unit. CNC's YCKB7 covers up to 63 A. It saves panel space, cuts wiring, and gives a motor coordinated...

Quick answer: A modular contactor is a quiet, DIN-rail-mounted switch that turns a circuit on and off from a low-power control signal — used for lighting banks, water heaters, pumps, and home/building automation, not for starting motors. It clips into your distribution board like an MCB. CNC's YCCH6 (standard) and YCCH7 (with manual override)...

Quick answer: An EV charger needs a dedicated earth electrode with a measured resistance below 5 ohms — and it has to be measured with an earth tester, not assumed. This is the item most Pakistani installs skip or fake, and it quietly disables everything else: your RCBO can only clear a fault if there's...

Quick answer: An EV charger produces smooth DC leakage current under fault, and that blinds the ordinary Type AC RCD fitted in most Pakistani boards — so a normal RCD is never acceptable. You need one of two things: a Type A RCBO/RCD, but only if your charger has built-in 6 mA DC fault detection (check the...

Quick answer: A 7 kW single-phase EV charger draws about 30–32 amps continuously for hours at a time, so it needs a 40 A MCB — not a 32 A one. But the breaker is only half the job. On its own it does nothing to stop electrocution or a DC earth fault, so a 7 kW charger circuit...

A star-delta starter reduces a motor's starting current by first running the windings in star — which puts only 1/√3 of the line voltage across each winding — then switching to delta for normal running. This cuts both starting current and starting torque to about a third of their direct-on-line values. It is used...

To keep power on during load shedding you switch your load from the grid to a backup source — generator, inverter/UPS or solar. The device that does the switching is what matters: a manual changeover switch is cheapest but needs you present; an automatic changeover or ATS switches within seconds on its own; a...

A DOL (Direct-On-Line) starter connects a motor straight to full mains voltage using a magnetic contactor, with a thermal overload relay for protection and start/stop buttons for control. It is the simplest and cheapest way to start a three-phase motor — suitable up to roughly 5–7.5 kW, above which the full starting current (6–8 × running...

A utilization category is the IEC 60947-4-1 code stating what kind of load a contactor is proven to switch. The same contactor carries a different amp rating in each category — typically Ith ≥ AC-1 ≥ AC-3 ≥ AC-4 — because switching resistive load is far easier than switching a motor. An amp figure...

The small module wired across a contactor coil is a surge suppressor. Every time the coil de-energises, its collapsing magnetic field generates a spike of hundreds to thousands of volts. An RC snubber, varistor or diode absorbs that spike — protecting the controlling contact, the coil insulation, and nearby electronics.