Module 2 : Industrial Control Devices Flashcards
SCR (Silicon Controlled Rectifier)
Three-terminal PNPN device that acts as a gated diode. The gate terminal switches the device in allowing current to flow from anode to cathode.
Commutation
Interrupting current, such as through the various windings of a DC motor armature.
Ladder Logic
An industry standard which uses successive horizontal lines with symbols to represent the logic operation of a control system.
Relay Logic
A method of controlling industrial electric circuits by using relays and contacts.
Actuator
Lever, arm, or wand.
Positioner
A servomechanism that moves to persis location
Hydraulic actuators
Two types of interfaces used in robotic circuits
electrical and hydraulic
Single Pole switch
single pole switch only allows the current one circuit to pass through
(NO)
Normally Open
(NC)
Normally closed
Pole
Movable contact on the switch. A completely isolated circuit that is allowed to pass through the switch
Thow
The number of positions in which the switch can be set.
What term describes the number of completely isolated circuits that pass through a switch at a given time?
POLE
What term describes the total number of individual circuits that each pole is capable of controlling?
Throw
How are switched rated?
Switches are generally rated by their current-handling capability and the type of load they can control.
Which proximity switches are suitable for high-speed counting applications?
RF inductive proximity switches
Capacitive proximity switches can detect only ferromagnetic materials. (True/False)
False
What is one disadvantage of optical proximity sensor?
The object sensed must have a reflective surface.
VA
Volt Ampage
Calculation for the hold in Current
hold-in current= VA hold-in rating
______________
Coil voltage rating
Calculation for inrush current
inrush current = VA inrush coiling
________________
Coil voltage rating
How much current must flow to keep a relay latched?
Holding current
What configuration ensures that when one device. is energized the other remains de-energized?
Electrical interlock
A relay’s make rating is often five times it’s normal operating current? (True/False)
True
Seal-in circuit
A method of maintaining a current flow after a momentary switch has been pressed and released.
holding Contact
seal-in contact
A seal-in circuit is usually parallel with a switch? (True/False)
True
What maintains current flow to the control relay?
Holding Contact
Electromagnetic Contactor
High power relay Current-handling above 15 A heavy duty contacts for switching industrial loads. designed with a stationary core and moveable armature
How are electromagnetic contactors rated?
According to the size and type of load by National Electrical Manufacturers Association (NEMA)
Electromagnetic contactors can be rated in horsepower.
true/False
True
Overload relays and Circuit breakers can withstand repeated tripping and capable of reset.
Used in Excessive current flow in a industrial electronic circuit
How are overload relays classified ?
as either thermal or magnetic
Thermal overload relays
Respond to high temperature by overload current
Magnetic Overload relays
React ONLY to excessive current and Not by temperature
Most popular types of thermal relays are?
Metal alloy and Bimetal type
Solenoid
an electro-mechanical device used in industrial control circuits. Commonin robots with hydraulic controls.
How do solenoids differ from relays?
instead of controlling electrical power, solenoid valves generally control fluid power and have no contacts.
Hydraulic fluid is used to rotate rotary actuators, besides filling hydraulic cylinders (True/ False)
True
What are the ports called on a three-way solenoid valve?
Inlet, Outlet, exhaust.
What devices are often used to operate control valves?
Solenoids
Valve positions are used with feedback circuits (True /False)
TRUE
What does TDR do?
Provide a delayed switching action
What are 3 basic types of TDR?
Electromechanical, electropneumatic and electronic
What are 2 basic types of counters?
Mechanical or Electronic
2,9,13,16,20, 28,30
