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PART 75
PART 75
PART 75
PART 75
PART 75
100
Where shall disconnecting devices be installed in high voltage circuits? These disconnecting devices shall be equipped or designed in a manner that it can be determined by what method that the circuit is deenergized when the switches are open?
The shall be installed at the beginning of branch lines and designed in a way that visual observation can be used to determine if the switches are open.
100
What devices shall be marked for identification?
Circuit breakers and disconnecting switches
100
How shall high voltage feeder cable terminations and splices be made?
Manufacturer's specifications
100
How shall high voltage equipment used underground be grounded?
Effectively grounded to the high voltage ground
100
In under what conditions may underground high voltage power centers and portable transformers be moved while energized?
Special permission
200
May high voltage cables other than trailing cables be moved or handled at any time while energized and what is the exception to that?
No except when energized transformers are moved by special permit. The cables must be moved only by qualifed persons wearing approved and tested insulated wireman's gloves.
200
What type of record must be maintained by the operator concerning movement of power centers and transformers?
A record of all examinations in an approved book
200
Who do you love?
I love u too!!!
200
How many circuits serving three phase alternating current equipment be protected?
Suitable circuit breakers that are properly tested and maintained
200
What are three requirements concerning the location of circuit breakers be tested and examined and by whom?
Monthly be a qualified person
300
What are two requirements that must be met when testing low and medium voltage breakers?
1. visual examination 2. actuating any auxiliaries or control circuits which cause the circuit breaker to open
300
How soon must required adjustments or repairs on circuit breakers be made?
Immediately
300
What are the requirements for grounding three phase low and medium voltage circuits used underground?
A direct or derived neutral which shall be grounded through a suitable resistor
300
Low and medium voltage resistance grounded systems shall include a fail safe ground check circuit to monitor continuosly the grounding circuit to assure continuity. The ground check circuit shall cause the circuit breaker to open when what condition exists?
When either the ground or pilot check wire is broken or other no less effective device approved by the Secretary to assure such continuity.
400
Low and medium voltage cable couplers shall be constructed so that which conductor is broken first when the coupler is being disconnected and which conductor shall be broken last?
Ground check first and the ground conductor last.
400
What is the maximum voltage allowed for ground check circuits on low and medium voltage circuits?
40 volts
400
How shall ground conductors and ground check wires be attached to equipment frames?
Separate connectors when practical
400
Disconnecting devices on low and medium voltage circuits shall be in conjunction with the circuit breaker to provide what type of evidence tht the power is disconnected?
Visual evidence
400
How shall low and medium voltage circuit breakers be identified?
Marked for identification
500
How shall single phase loads be connected in low and medium resistance grounded systems?
Phase to phase
500
Medium voltage trailing cables are not required to be shielded on equipment employing cable reels if the insulation is rated for a minimum of how many volts?
2000 volts
500
Cutout switches must be provided on trolley wires and trolley feeder wires at intervals of not more than how many feet and near the beginning of all what type of lines?
Not more than 2000 feet and near the begining of all BRANCH lines
500
Trolley wires and trolley feeder wires, high voltage cables and transformers shall not be located inby the last open crosscut and shall be kept at least how many feet from pillar workings?
150 feet
500
If an electric motor is used to drive a main mine fan, the motor shall be operated from what type of power circuit?
Independent of all main power circuits