By what means is the burning of controller...

🔍 Key Concepts

• Electrical arcing in switches and controllers – what happens when you interrupt current in a magnetic field • How contacts are protected in high‑current DC or AC motor controllers • Difference between protective releases (overcurrent/overvoltage) and devices that physically move or stretch the arc

💭 Think About

• Think about which choice actually acts on the arc itself at the contacts, rather than just tripping or releasing the circuit on a fault condition. • Which option would be used specifically in high-current controllers (like motor starters) to lengthen, move, or extinguish the arc when the contacts open? • Consider whether applying a substance on the contacts is standard marine electrical practice for arc prevention, or if that would cause other problems like contamination or heating.

✅ Before You Answer

• Identify which options are protective trip devices and which one is a mechanism to control the arc path. • Ask: which method is commonly used in DC motor controllers and contactors to ‘blow’ the arc away from the contacts? • Verify whether any standard electrical practice recommends petroleum jelly on contact faces, or if contact surfaces are usually kept clean, flat, and properly aligned instead.

By what means is the burning of controller contacts due to arcing, when opening, prevented?

an over current release

an overvoltage release

coating the contact surfaces lightly with petroleum jelly

magnetic blowout coils

🔍 Key Concepts

💭 Think About

✅ Before You Answer