Capacitors and Starting Relays

Question 1

What is a Current Relay?

Answer 1

• used on motors under 1/2 HP
• removes start capacitor from circuit
• used on Hermetic compressors
• normally open contacts
• coil energized by high starting current and opens when amperage lowers (75% of rated speed)
• ## used on fixed metering systems

Question 2

What is a start capacitor?

Answer 2

• increases starting torque
• required on most TEV system
• has a bleed resistor
• no oil
• 60 - 700 MFD
• never replace with smaller MFD ratings
• 130 % of the original size

Question 3

What are Potential Relays?

Answer 3

• used on single phase compressors up to 5 HP
• removes start capacitor out of circuit
• Normally closed contact
• voltage energizes relay coil to open circuit with back EMF

Question 4

What are Run Capacitors?

Answer 4

• increases running efficiency
• oil filled for cooling
• stays in the circuit while motor is running
• smaller MFD rating compared to start cap
• 3 - 70 MFD
• never replace with lower values. Can replace with larger but up to 110% of its original size