H1gh V0ltage Flashcards
Line that connects between generating station and next substation XFMR
Transmission line
According to IEEE what voltage is medium voltage?
2.4kv-69kv
Between what voltage utility companies generate
10kv-20kv
Invisible field of force that surrounds conductors
Electrostatic Field
Name given to electrostatic field with flux density from centre
Voltage gradient
Cleaning insulator bushings diminish
Creepage distance and tracking
Insulation used on power equipment must withstand
Basic impulse insulation level
Which high voltage distribution system offers supply from 2 directions
The ring system
According to CEC what is the minimum working space around 45kv equipment
2.5M
How are lightning arresters connected on lines
In parallel with each phase to ground
How does series reactor limit current or choke current
By increasing its inductive REACTANCE
500/5 c.t has 4 loops secondary reads 5 amps what is primary
125a
What would best selection of a c.t if primary between 350-400amps
500/5
What is best VT ratio if primary is 230V
1100/1
Key interlocking is a system designed
Offer protection to equipment and personnel
What is the steps in order to a safe switching procedure
Disconnect Lockout Test Ground Screen off
What is the minimum safe working distance from 250kv line
15ft
According to CEC do VT’s require overprotection on supply side
Yes must have over current protection and disconnecting means
On gang operated switch handles, according to CEC
1.2M X 1.8M
According to CEC what is tolerable touch voltage on dry soil
405v
The ability of dielectric for HV cable to withstand breakdown
Dielectric strength
What is primary purpose of strand shields
Remove flux lines in air voids
Which termination class is approved for indoor termination
Class 1
According to CEC shielding is required over all thermoset insulated cables
5000V
What is the bending radius of 45mm aluminum
675mm
Are we allowed to install HV cables in elevator shafts.
Yes in conduit in 50mm concrete
Which type of switches can interrupt small load currents
Horn gap switch
Which switch uses hotstick
Isolating
What type of HV fuse is non-expulsion type
Current- limiting
What determines the short circuit current
Transformer % impedance
What provides force to close contacts
Charged springs
Which HV breaker may close its contacts more than once automatically
Recloser breakers
