Flashcards
Operation of Transformers (Mod.5 Sect.4 Part 1)
Cards in this deck (33)
- 1A _______ changes, or transforms, an AC voltage to a higher or lower AC voltage.transformer
- 2The main parts of a transformer are the two _____ and the _______.coils, iron core
- 3The two coils in a transformer are called the _______ winding and the _______ winding.primary, secondary
- 4A transformer's _________ winding is connected to an electrical load.secondary
- 5A transformer's _________ winding is in a closed circuit with an AC voltage source.primary
- 6When a voltage is applied to the primary, a voltage is ________ (produced) in the secondary and the AC current flows through the load.induced
- 7The voltage applied to the primary is called the ________ voltage, and the voltage induced in the secondary is called the ________ voltage.primary, secondary
- 8The relative movement between magnetic ____________ and a conductor can generate/produce a voltage.lines of force
- 9In a transformer, the conductors don't move, but the magnetic lines of force change when the ___________ changes.applied voltage
- 10______________ are created by the applied voltage and change with any variation of it.Magnetic lines of force
- 11Magnetic lines of force are also called _____.flux
- 12The voltage induced in the secondary is proportional to the ______ in the magnetic lines of force.change
- 13Transformers can only change/transform ____ voltages.AC
- 14If the secondary winding has more turns than the primary, the secondary voltage will be ______ the the primary voltage.greater
- 15If the secondary winding has fewer turns than the primary, the secondary voltage will be _______ the primary voltage.less than
- 16A transformer that steps down the secondary voltage is called a ________ transformer.step-down
- 17A transformer that steps up the secondary voltage is called a ________ transformer.step-up
- 18The transformation of voltage depends on the ratio of the number of turns on the primary to the number of turns in the secondary. This is called the __________.turns ratio
- 19__________ transformers are transformers with equal primary and secondary windings; the voltage isn't transformed.Isolation
- 20__________ transformers are often used to isolate two circuits without changing their voltages. They're also used by technicians for safety when working on ungrounded equipment.Isolation
- 21A ________ condition is when the switch is open in the secondary circuit.no-load
- 22A ______ condition is when the switch in the secondary circuit is closed.load
- 23In an ideal transformer under ______ conditions, the power in the primary circuit is equal to the power in the secondary circuit.load
- 24Step-up/down transformers have different voltages & currents in their primary and secondary circuits, but the _____ in each circuit stays the same.power
- 25The strength of a transformer's magnetic field is called _____________.magnetomotive force
- 26Magnetomotive force is measured in _________.ampere-turns
- 27Transformers are often rated in terms of __________ or __________.volt-amperes (VA), kilovolt-amperes (kVA)
- 28A transformer should be selected that's the next _______ standard kVA rating than calculated. This prevents failure and heat buildup. It also allows for future expansion of the circuit controlled by the transformer.highest
- 29Making a transformer's core out of _______ instead of a solid core helps to reduce eddy current losses.laminations
- 30_________ are thin sheets of magnetic iron.Laminations
- 31The change in secondary voltage resulting from applying a load to a transformer, divided by the full load secondary voltage is called the _______ of the transformer.regulation
- 32A change of voltage in one coil that leads to a voltage in another nearby coil is a result of ______ inductance.mutual
- 33The current that flows in the transformer primary with no load connected to the secondary is called the _______ current.exciting