PE Controls Flashcards
Black conductor color generally indicates what?
Line, load, and control circuits at line voltage
Red conductor color generally indicates what?
AC control circuits less than line voltage
Blue conductor color generally indicates what?
DC control circuits
Yellow conductor color generally indicates what?
Interlock control circuits powered from external power supply
Green conductor color generally indicates what?
Equipment ground conductor where insulated or covered
Red color pushbuttons generally indicate what?
Emergency stop, Stop, Off
Yellow color pushbuttons generally indicate what?
Return, Emergency return, Intervention – suppress abnormal conditions
Green color pushbuttons generally indicate what?
Start, On
Per NFPA 79 (Industrial Machinery), power circuit conductors shall not be smaller than what size conductor?
14 AWG
Per NFPA 79 (Industrial Machinery), lighting and control circuits on machine and in raceways conductors shall not be smaller than what size conductor?
16 AWG
Per NFPA 79 (Industrial Machinery), control circuit conductors shall not be smaller than what size conductor?
18 AWG
Per NFPA 79 (Industrial Machinery), electronic and control conductors in raceways conductors shall not be smaller than what size conductor?
24 AWG
What industry standard covers proper grounding techniques for loading stations where static electricity hazards may occur?
NFPA 77
What are the recognized means by which lightning induced voltage surges occur in mains or data/telecommunications cables?
Resistive coupling, inductive coupling, capacitive coupling
What industry standard covers proper grounding techniques for lightning protection?
NFPA 78
What industry standard covers wire sizing and color codes in industrial machinery?
NFPA 79
What industry standard covers various environmental enclosure ratings?
NEMA 250
A 480 volt three phase 50 HP motor draws 65 amps and is 600 feet away. What is the voltage drop, and what size wire should we use for a 5% voltage drop?
24volts drop maximum; 33,774cm (area circular mils; cm = ((sqrt(3) * L * I * k) / Vd); #4 AWG; k is specific resistance (k = ((R * cm) / 1000)
What is the voltage drop for AWG 18 stranded wire 565 feet one way in coated cable? Wire carries 20 mA of dc current. Note: Coated (wires are jacketed); uncoated (wires are not jacketed).
191mV ((Vd = ((2*L) / 1000) * I * R)
What is the DC voltage drop formula?
Vd = ((2 * L) / 1000) * I * R)
What is the AC single phase voltage drop formula?
Vd = (((2 * L) / 1000) * I * Ze); (Ze with p.f. = 100 is equal to dc = R)
What is the AC three phase voltage drop formula?
Vd = (((sqrt(3) * L) / 1000) * I * Ze); (Ze with p.f. = 100 is equal to dc = R); (Note: ((2 * L) / 1000) * I * Ze * Cos30) = (((2 * L) / 1000) * I * Ze * (sqrt(3) / 2)) = (((sqrt(3) * L) / 1000) * I * Ze)
