🔍 Key Concepts

• Magnetic contactor operation – how the coil pulls the contacts together and what keeps them closed • Arcing at contacts – what operating condition makes contacts chatter or not fully close, leading to heat and possible welding • Effect of coil voltage and coil condition on the strength of the magnetic field

💭 Think About

• Think about which option would cause the contacts to make poor or incomplete contact so that they arc and overheat, rather than just sit firmly open or firmly closed • Ask yourself: in normal operation, when are contacts most likely to spark – when the electromagnet is strong and solid, or when it is weak or unstable? • Consider what happens to a contactor if the coil is not getting its proper voltage. How would that change the way the armature pulls in and holds the contacts?

✅ Before You Answer

• Which choice would most likely cause chattering or weak closing of the contacts, leading to arcing and heat buildup? • Which choices would more likely keep the contacts either fully open (no heat) or firmly closed (less arcing)? • Verify which condition directly affects the strength of the magnetic field produced by the operating coil, and thus the contact pressure during operation.