Basic Installation Procedures

Question 1

A PLC is best mounted in a motor control centre. True or False?

Answer 1

False

Question 2

Communication cables must be kept a minimum of ____mm from power cables and cross the power cables at ________

Answer 2

300mm, right angles

Question 3

Grounding and shielding is done in a _______ fashion to prevent ________ loops

Answer 3

radial, ground

Question 4

Does the CEC allow the load side of a DC power supply (system) to be left ungrounded? What is usually done? Why?

Answer 4

Yes. CEC Rule 10-102(1) allows this if it is not more than 50V. It is usually grounded anyway, to prevent the above-ground potential from becoming excessive through static charging, misconnection or wiring fault.

Question 5

What are five possible CPU power supply sources in order from least to most preferable

Answer 5

• Raw line power
• Isolation transformer
• Regulating transformer
• Power conditioner
• UPS

Question 6

What are four reasons to include a master control relay in a PLC program?

Answer 6

Override for:

• PLC hardware failure
• Programming blunders
• Some wiring mistakes
• Provide low-voltage protection