🔍 Key Concepts

• Megohmmeter (megger) operation when testing insulation resistance • How winding insulation behaves like a capacitor when voltage is first applied • Difference between steady insulation resistance and transient charging effects on the meter pointer

💭 Think About

• When you first apply DC test voltage from a megohmmeter to a large motor winding, what electrical effect happens before the reading settles? • Does a large coil of wire with insulation act only like a resistor, or does it also have another property that temporarily allows current flow? • Which choice describes something that would cause a brief, momentary current that quickly dies away, rather than a constant low-resistance reading?

✅ Before You Answer

• Recall that a megohmmeter applies DC voltage and measures resistance based on current flow • Think about how a coil of insulated wire can store charge between conductors and ground or between turns • Ask: Which option would cause a short-lived pointer deflection that quickly recovers, not a permanent low reading?