Transformers calculations

• What is the purpose of transformers in electricity supply?

  To change the voltage of an electricity supply
• How do step-up transformers increase voltage?

  They have more turns on the secondary coil than on the primary coil
• How do step-down transformers decrease voltage?

  They have less turns on the secondary coil than on the primary coil
• What do the variables in the transformer equations represent?

  Vp : Primary voltage

  Vs : Secondary voltage

  Ip: Primary current

  Is: Secondary current

  Np: Number of turns in primary coil

  Ns: Number of turns in secondary coil
• Given a primary (initial) voltage of 45 volts, how do you calculate the secondary (output) voltage for a transformer?

  Use the equation Vp/Vs = Np/Ns
• What is the output Voltage/potential difference (Vs) if Np = 18, Ns = 54, and Vp = 45 volts?

  Output Voltage/ P.D (Vs) = 135 volts
• If the primary (input) current (Ip) is 12 amps, how do you find the secondary (output) current Is ?

  Use the equation Vp x Ip = Vs x Is
• What is the secondary current is if Ip = 12 amps, Vp= 45 volts, and Vs= 135 volts?

  Secondary current is = 4 amps
• What are the two main equations used in transformer calculations?

  ​1. Vp/Vs = Np/Ns

  2. Vp x Ip = Vs x Is