Introduction to PLC lessons 1-4
Tinted , arc-rated ? should be warn when working on any PLC system that has voltages over 50 volts or in any environment where arc flashes are possible
face shields
number of I/O in a NANO PLC
less than 16 I/O
PLC's provide rigid control for cycle automation, minimizing ?
manual intervention
Number of I/Os in a Large PLC
more than 512
What industry would use a PLC to monitor a corrugation machine
pulp and paper
common terms used to describe DC positive polarity
source or supply
Why must technicians wear insulating electric gloves and use insulated tools to test instruments?
to prevent resistance
A ? is used to manage wire connections between PLC Inputs/outputs and electrical devices/components
Terminal block
A ? switch circuit typically uses a sink or source transistor as the switching device
Three wire input NPN (sink) PNP (source)
What is a Modular form factor PLC
Variable number of input/output terminals base on cards or modules
Briefly describe steps of inspecting PLC
1) ensure the PLC and all associated hardware is securely mounted in a proper location 2) check all wire connections 3) grounding
List three examples of input devices
1) push button 2) prox switch 3) Selector switch 4) limit switch
PLCs using a fixed voltage for the power supply are typically rated at ? Volts
115 VAC +5% to -10%
number of I/Os in a medium PLC
129- 512
Number of I/Os in a Micro PLC
16-128
What are the common resistance values for grounding electronic equipment that manufactures often specify
5 ohms 3 ohms 1 ohm or less
how many bits are in a byte
8
what type of Gate logic is represented by any number of normally opens switches connected in series
AND Logic
Output such has lights, motors, and valves are typically connected as what type of circuit
Parallel
Why must extra care be taken when using a force command
Because it overrides all safety features
A PLC ? overheat and become a fire hazard
Can
common terms used to describe DC negative polarity
Common or sink
Example of the function of a PLC in an elevator system
Direct the lift accordingly
what is the formula to determine total resistance in a series circuit
E/I= R
Will the total resistance in a parallel circuit always going to be higher or lower than the lowest resistance value of any given load
Lower
Normally closed (NC) switch that is ? operated will have the operator of the switch drawn above the terminals of the switch
Mechanically or automatically
What size of PLC's typically contain rack mounted I/O modules
Medium/large
The output sections of ? PLC's have 6 relay contacts
Micro
the input section of a ? PLC contains 4-6 digital and 2-4 analog input terminals, while the output section has 4 relay contacts
Nano
What type of electric equipment are PLC's considered to be that requires them to be mounted in and enclosure
Open Type
what is the function of a PID instruction
Output instruction used to control set point of a variable inside control logic. ( temp, flow, pressure, level)
Wha is the function of the housekeeping and overhead section of the operating cycle
PLC performs memory management and updates timers and counters
What is the most common programming device used to program PLCs
Personal computers
Symbol for an activated (NO) manual switch
Pg 120
A ? is helpful in showing what additional components can be added to a system and what function a device or component has within the system
Pictorial Drawings
What type of devices are bit instructions programmed for
Relay type device
The voltage drop across any two loads are the same if the ? values of the loads are the same
Resistance
How are bits numbered
Right to left starting at 0
what is a program scan
Section of operating cycle in which PLC examines PLC program compares program status inputs determine output
In a ? circuit, current stops flowing any time a fuse blows, a circuit breaker trips or a switch opens
Series
what is a Fixed Form Factor PLC
Set number and type of input and out put terminals
Regarding PLC installation guidelines what do all PLC installations start with
Sufficient number of emergency stops and a master control relay
The standard unit of of memory for a PLC is the ?
Word
Describe the point to point wiring method
where each component in a circuit is connected (wired) directly to the next component as specified by wiring or line diagrams
