🔍 Key Concepts

• Electric motor starters and contactors – how contacts open/close under load • Arcing and heat buildup when starting large motors • Effect of high current vs. mechanical motion/pressure on contact surfaces

💭 Think About

• Which option would cause enough heat at the contact surface to actually fuse (weld) metal together, rather than just cause wear? • Think about what happens to current when a large motor first starts – is it higher or lower than running current, and how does that affect contacts? • Which options are mainly about mechanical movement, and which are mainly about electrical load and heating?

✅ Before You Answer

• Identify which choice directly involves very high current through the contacts rather than just how fast they move • Consider which situation would create sustained intense arcing/heat at the instant of closing • Eliminate any options that don’t clearly connect to overheating of the contact surfaces