Rheostat/Potentiometer/ Dynamic Breaking/Capacitors

How Does Dynamic Braking work

When the Armature is

disconnected from supply

voltage and immediately

connected to the Brake Resistor

and still rotating, it will generate

a current which will pass through

the resistor

Does Dynamic Braking Require little or a lot of Wattage?

Dynamic Braking need to have high wattage ratings because of the potentially large amount of CEMF current

What happens to CEMF when using Dynamic Braking

It gets routed through the resister

List 3 types of capacitors

• Electrolytic Capacitors

• Polarized Variable Capacitors

• Non Polarized Capacitors

What device Opposes a change in Voltage?

• Capacitor

What are Capacitors Rate for?

• Capacitance

• Voltage

How is Capacitance Measured

Farads

How can a Capacitor be used (2 ways)

• As a Battery

• As a Filter

How is a Capacitor built

• Dielectric Material sandwiched between two Plates

What are 3 factors that determine the amount of Capacitance a Capacitor has?

• Type of Dielectric Material used

• Distance between the plates

• Surface area of the places

When can Current pass through a Capacitor?

• Only when it is changing or Discharging

How Many time constants are needed to Charge and discharge a Capaticor

• 5 - there are 5 time constants in a Capacitor Time cycle

What percentage does each Time constant represent?

• 63.2%

Capacitors are used to reduce what?

• Ripple Voltage

How does a Capacitor reduce Ripple Voltage?

• It acts as a filter to smooth out the voltage of rectifiers

How are Capacitors connects

• parallel with the load