MICHELIN ECT FINAL EXAM
QUESTIONS AND ANSWERS 2026
VERIFIED.
Continuous Current Rating - ANS The current that the fuse is intended to normally carry
indefinitely, considering load type, application, and code requirements.
Interrupting Rating - ANS The maximum short circuit current that a fuse can safely interrupt
without rupturing, as required by the National Electric Code.
Current Limiting - ANS Associated with short circuit conditions, a fuse is current limiting if it
operates quickly under short circuit conditions, limiting the peak short circuit current.
Selective Coordination - ANS The need to prevent facility blackouts by ensuring that only the
protective device nearest the faulted circuit opens, maintaining a specific ratio between
upstream and downstream continuous current ratings.
What is the formula for Xl? - ANS 2(pi)fl
Ohm's Law - ANS Current is directly proportional to voltage and inversely proportional to
resistance
@2026/2027 ALLRIGHTS RESERVED.
,Kirchoff's Series Law - ANS The sum of the voltages drops around a circuit loop must be equal
to the applied voltage
Power Formula - ANS VxI
Kirchoff's parallel law - ANS The sum of the currents entering a junction must equal the sum
of currents leaving the junction
How do inductive prox. switches work? - ANS The oscillator circuit generates an
electromagnetic field, when a metallic object approaches the sensor, it disrupts the
electromagnetic field and induces eddy current in the metal object. The sensor detects the
change in emf and triggers the output.
Hysteresis - ANS Prevents chattering
How do capacitive prox. switches work? - ANS When an object comes close to the sensor it
alters the electric field between the two conductive plates, the change in the dielectric constant
affects the capacitance. An oscillator inside the switch detects the changing capacitance and
triggers a signal.
Light mode - ANS Output is on whenever the receiver can see light from the light source.
Dark mode - ANS Output is on whenever the receiver cannot see light from the light source.
Photocell - ANS A sensor that uses light to detect the presence or absence of an object.
Transmitted Beam Photocell - ANS A photocell that has two parts, the emitter and receiver, in
two different housings opposite each other.
@2026/2027 ALLRIGHTS RESERVED.
,Retroreflective Photocell - ANS A photocell where the emitter and receiver are in the same
housing. A reflective material is placed where the photocell is facing.
Diffuse Photocell - ANS A sensing mode in which light strikes an object surface and is diffused
from the surface at all angles and detected by the sensor.
How do ultrasonic prox. switches work? - ANS Ultrasonic sensors work by emitting and
receiving high-frequency sound waves. Uses either oppose or diffuse mode.
Where are contactors found? - ANS In both the power and the control circuit.
What is the difference between a contactor and a relay? - ANS The contacts on a contactor
are rated for a higher voltage than the relay contacts.
How are eddy currents reduced in a contactor/relay? - ANS The stationary core is constructed
of laminated steel.
How are vibrations reduced in contactors/relays? - ANS Shading rings.
What is a CRM? - ANS Control relay master, a relay used to monitor all the safety devices and
de-energize if one opens.
What are the two basic types of overload relays? - ANS Thermal type and electronic current
monitoring type.
@2026/2027 ALLRIGHTS RESERVED.
, What are the three reasons an overload trips? - ANS Prolonged overcurrent (105% to 130%
full load current), phhase unbalance, and phase loss/single phasing.
Off delay timer - ANS Closes/opens the timed contacts instantly, then timer starts after the
coil gets de-energized. Has an arrow pointing down on the symbol.
On delay timer - ANS Closes/opens the timed contacts after the set time, then when the coil
is de-energized, the contacts go back to normal instantly. Has an arrow pointing up on the
symbol.
What is an auxiliary block? - ANS An addon black that adds extra contacts to a relay or
contactor.
What is capacitance? - ANS A capacitor can store electrical energy and also return this
electricity to the circuit. Capacitance is the property of a component which allows it to store
electrical energy
How does a solenoid work? - ANS A solenoid is an electrically controlled valve that operates a
mechanical valve.
What is peak voltage in AC? - ANS The maximum voltage, can be wrote as Vpeak or Vmax
What is the effective voltage called in AC? - ANS RMS voltage, or root mean square voltage
How is RMS voltage calculated? - ANS Vmax multiplied by .707
How is instantaneous current found? - ANS Ii = Imax x sin(phase angle)
@2026/2027 ALLRIGHTS RESERVED.
QUESTIONS AND ANSWERS 2026
VERIFIED.
Continuous Current Rating - ANS The current that the fuse is intended to normally carry
indefinitely, considering load type, application, and code requirements.
Interrupting Rating - ANS The maximum short circuit current that a fuse can safely interrupt
without rupturing, as required by the National Electric Code.
Current Limiting - ANS Associated with short circuit conditions, a fuse is current limiting if it
operates quickly under short circuit conditions, limiting the peak short circuit current.
Selective Coordination - ANS The need to prevent facility blackouts by ensuring that only the
protective device nearest the faulted circuit opens, maintaining a specific ratio between
upstream and downstream continuous current ratings.
What is the formula for Xl? - ANS 2(pi)fl
Ohm's Law - ANS Current is directly proportional to voltage and inversely proportional to
resistance
@2026/2027 ALLRIGHTS RESERVED.
,Kirchoff's Series Law - ANS The sum of the voltages drops around a circuit loop must be equal
to the applied voltage
Power Formula - ANS VxI
Kirchoff's parallel law - ANS The sum of the currents entering a junction must equal the sum
of currents leaving the junction
How do inductive prox. switches work? - ANS The oscillator circuit generates an
electromagnetic field, when a metallic object approaches the sensor, it disrupts the
electromagnetic field and induces eddy current in the metal object. The sensor detects the
change in emf and triggers the output.
Hysteresis - ANS Prevents chattering
How do capacitive prox. switches work? - ANS When an object comes close to the sensor it
alters the electric field between the two conductive plates, the change in the dielectric constant
affects the capacitance. An oscillator inside the switch detects the changing capacitance and
triggers a signal.
Light mode - ANS Output is on whenever the receiver can see light from the light source.
Dark mode - ANS Output is on whenever the receiver cannot see light from the light source.
Photocell - ANS A sensor that uses light to detect the presence or absence of an object.
Transmitted Beam Photocell - ANS A photocell that has two parts, the emitter and receiver, in
two different housings opposite each other.
@2026/2027 ALLRIGHTS RESERVED.
,Retroreflective Photocell - ANS A photocell where the emitter and receiver are in the same
housing. A reflective material is placed where the photocell is facing.
Diffuse Photocell - ANS A sensing mode in which light strikes an object surface and is diffused
from the surface at all angles and detected by the sensor.
How do ultrasonic prox. switches work? - ANS Ultrasonic sensors work by emitting and
receiving high-frequency sound waves. Uses either oppose or diffuse mode.
Where are contactors found? - ANS In both the power and the control circuit.
What is the difference between a contactor and a relay? - ANS The contacts on a contactor
are rated for a higher voltage than the relay contacts.
How are eddy currents reduced in a contactor/relay? - ANS The stationary core is constructed
of laminated steel.
How are vibrations reduced in contactors/relays? - ANS Shading rings.
What is a CRM? - ANS Control relay master, a relay used to monitor all the safety devices and
de-energize if one opens.
What are the two basic types of overload relays? - ANS Thermal type and electronic current
monitoring type.
@2026/2027 ALLRIGHTS RESERVED.
, What are the three reasons an overload trips? - ANS Prolonged overcurrent (105% to 130%
full load current), phhase unbalance, and phase loss/single phasing.
Off delay timer - ANS Closes/opens the timed contacts instantly, then timer starts after the
coil gets de-energized. Has an arrow pointing down on the symbol.
On delay timer - ANS Closes/opens the timed contacts after the set time, then when the coil
is de-energized, the contacts go back to normal instantly. Has an arrow pointing up on the
symbol.
What is an auxiliary block? - ANS An addon black that adds extra contacts to a relay or
contactor.
What is capacitance? - ANS A capacitor can store electrical energy and also return this
electricity to the circuit. Capacitance is the property of a component which allows it to store
electrical energy
How does a solenoid work? - ANS A solenoid is an electrically controlled valve that operates a
mechanical valve.
What is peak voltage in AC? - ANS The maximum voltage, can be wrote as Vpeak or Vmax
What is the effective voltage called in AC? - ANS RMS voltage, or root mean square voltage
How is RMS voltage calculated? - ANS Vmax multiplied by .707
How is instantaneous current found? - ANS Ii = Imax x sin(phase angle)
@2026/2027 ALLRIGHTS RESERVED.
