Name the three categories of timers. - ANSWER Dashpot, synchronous
clock, electronic timers.
What are two types of solid-state relays? - ANSWER NPN or PNP
transistors, and SCRs
What are the three types if ac motors? - ANSWER Series,
synchronous, and induction.
Describe a ladder diagram. - ANSWER Two rails L1 and L2 with ladder
rungs, input and output
What five conditions may cause excessive hum in a magnetic
assembly? - ANSWER (1) broken shading coil; (2) operating voltage to
low; (3) wrong coil; (5) dirt, rust, etc.; (6) jamming or binding of moving
parts;.
Describe a relay? - ANSWER A device designed for remote control of
another device.
What is inductive reactance? In what unit is it measured? - ANSWER
An opposition to current flow. Is measured in ohms
What does continuous rating mean? - ANSWER The rating for current
relay contacts handling when holding a circuit closed for some time.
What does inductive rating mean? - ANSWER The load it must handle.
What is the difference between an SCR and a triac? - ANSWER SCR
conducts in one direction and a triac conducts in both directions. An
SCR can handle higher currents than a triac.
, What is the right-hand rule of a motor? - ANSWER Use the right hand
with the thumb in the direction of the motor rotation and the index finger
pointing in the flux direction, now the middle finger indicates current flow
direction.
What does resistive rating mean? - ANSWER Resistive rating load
capacity when switching resistive (resistor) loads.
What is the inductive reactance if the frequency is 120Hz and there are
17Henrys of inductance? - ANSWER XL = 12817Ω
A 10Ω, 200Ω, and 500Ω are connected in series. What is the total
resistance and what is the current if it its connected to a 12V source -
ANSWER RT = 710 Ω I = 17 mA
What is the torque of a motor that is rated at 150HP and rated at 4200
RPM? - ANSWER Torque = 188 lb/ft
What is the horse power of a motor that has a 200 lb/ft torque and runs
at 4200 RPM? - ANSWER HP = 160
A 6500Ω, 35000Ω and 22000Ω are connected in parallel. The current
across the 35000Ω resistor is 20 mA. What is the current across the
other two resistors. - ANSWER E = 700V I = 108mA I = 32 mA
If a 5HP motor is connected to 240V. What is the current? - ANSWER I
= 15.5 A
What is the RPM of an induction motor where the frequency is 60Hz and
there are 6 poles? - ANSWER RPM = 1200
Symbols - ANSWER Solenoid, SPST relay, Tapped resistor, NO flow
switch, Adjustable Inductance transformer
What is jogging? How is it done? - ANSWER Inching of motor, with
start stop station
clock, electronic timers.
What are two types of solid-state relays? - ANSWER NPN or PNP
transistors, and SCRs
What are the three types if ac motors? - ANSWER Series,
synchronous, and induction.
Describe a ladder diagram. - ANSWER Two rails L1 and L2 with ladder
rungs, input and output
What five conditions may cause excessive hum in a magnetic
assembly? - ANSWER (1) broken shading coil; (2) operating voltage to
low; (3) wrong coil; (5) dirt, rust, etc.; (6) jamming or binding of moving
parts;.
Describe a relay? - ANSWER A device designed for remote control of
another device.
What is inductive reactance? In what unit is it measured? - ANSWER
An opposition to current flow. Is measured in ohms
What does continuous rating mean? - ANSWER The rating for current
relay contacts handling when holding a circuit closed for some time.
What does inductive rating mean? - ANSWER The load it must handle.
What is the difference between an SCR and a triac? - ANSWER SCR
conducts in one direction and a triac conducts in both directions. An
SCR can handle higher currents than a triac.
, What is the right-hand rule of a motor? - ANSWER Use the right hand
with the thumb in the direction of the motor rotation and the index finger
pointing in the flux direction, now the middle finger indicates current flow
direction.
What does resistive rating mean? - ANSWER Resistive rating load
capacity when switching resistive (resistor) loads.
What is the inductive reactance if the frequency is 120Hz and there are
17Henrys of inductance? - ANSWER XL = 12817Ω
A 10Ω, 200Ω, and 500Ω are connected in series. What is the total
resistance and what is the current if it its connected to a 12V source -
ANSWER RT = 710 Ω I = 17 mA
What is the torque of a motor that is rated at 150HP and rated at 4200
RPM? - ANSWER Torque = 188 lb/ft
What is the horse power of a motor that has a 200 lb/ft torque and runs
at 4200 RPM? - ANSWER HP = 160
A 6500Ω, 35000Ω and 22000Ω are connected in parallel. The current
across the 35000Ω resistor is 20 mA. What is the current across the
other two resistors. - ANSWER E = 700V I = 108mA I = 32 mA
If a 5HP motor is connected to 240V. What is the current? - ANSWER I
= 15.5 A
What is the RPM of an induction motor where the frequency is 60Hz and
there are 6 poles? - ANSWER RPM = 1200
Symbols - ANSWER Solenoid, SPST relay, Tapped resistor, NO flow
switch, Adjustable Inductance transformer
What is jogging? How is it done? - ANSWER Inching of motor, with
start stop station
