switchgear Flashcards
What is a TVSS?
Transient Voltage Surge Suppressor, It is a device that protects electrical devices from voltage spikes by shorting them to ground. Advanced: Metal Oxide Varistor Base
What is a SPD?
Surge Protection Device
What is a HRG?
High Resistance Ground used to decrease fault amperage within a circuit. Reduces fault current to >5A
What is a HMI?
Human Machine Interface
Concerning HMI’s, what are some accessible screens. What type of information is provided by each of these screens.
a) Breaker/ Trip unit
b) Current screen: tells you the amps on each phase
c) Voltage screen: tells you the volts on each phase
d) Analog Meter: tells you current
e) A multi-screen with settings: protection, advanced, about, test and measurement screens.
What is a breaker?
Automatically opens, manually operated electrical switch designed to isolate and protect down stream electrical equipment from shorts or overloads
What are common breaker sizes on site?
5000A, 4000A, 3000A, 1600A, 800A, 400A
What is a trip unit?
A trip unit is the part of the circuit breaker that opens the circuit in the event of overload, short circuit, or ground fault condition
Discuss LSIG settings (Long time, short time, instantaneous and ground)
Long Time(overload protection, analogous to the inverse-time thermal trip of a thermal/magnetic breaker) , Short Time(short circuit protection of low level faults), Instantaneous(short current protection of high level faults, analogous to the instantaneous magnetic trip of a thermal/magnetic breaker), Ground Fault(equipment ground fault protection)
What do you need prior to resetting a tripped breaker over 32A?
Identify the trip, the cause of the trip, mitigate failed components, FM Permission, FE permission
What is ground fault and how can the ground fault trip be tested on a power circuit breaker?
Ground Fault is contact between an energized conductor and ground. The test button on the breaker shorts the neutral wire feeding the load
What is a rating plug? What effect will it have on the breaker if the rating plug is removed
Rating Plugs allow the effective ampere rating of the circuit breaker to be modified within a range of 50-100 percent of the breaker’s frame ampere rating. Also allows breaker to be programmed with multiple trip ratings. SIte Specific responses could include: Revert to manufacturer specification in Long term and/or Instantaneous. EATON: Will open breaker? (Investigate)
What is the Basler (or other equivalent protective relay device) and what is its Purpose?
Basler is a compact multifunction numeric sensing relay that provides phase, zero sequence, and negative sequence voltage including over and under frequency, plus control and metering functions in an integrated system.
What are the sources for switchgear control power?
Site specific 120V: HUPPS, UPS, Utility, Generator; 24V (Advanced): Phoenix UPS(redundant in Catcher Boards), Cross-tie from Parallel Board
Name the ways you can start the generator from the switchgear?
Turn Utility Main Breaker off, Battle switch, PLC, AMCOP, voltage sensing breakers site specific
What is the purpose of the tower beacon assembly and what do the following colors signify:
a. Red Auto fail
b. Yellow Load on Generator
c. Green PLC in Auto
d. Blue Dead Bus
e. No Light PLC in Manual
What is switchgear auto-fail, what can cause auto-fail, and how is it reset?
Any time it goes into a control sequence and cannot complete the command, causes: Switch in manual, breaker malfunction Reset: Based on site equipment, AMCOP / PLC
What is the difference between open and closed transition (make-before break vs break-before-make)
Open transitions - breaks contact with one source of power before it makes contact with another source of power. Closed transition – makes contact with one power source before it breaks contact with another power source.
Explain how to rack a breaker in/out.
Rack in 1 – Remove disconnection crank from its housing. 2 – Press the lock pushbutton and insert the crank in the moving part. The moving part is still in DISCONNECT position. 3 – Turn the crank clockwise until the pushbutton comes out and the indicator shows that the circuit breaker is in TEST position. 4 – Press the lock button and then rotate the crank clockwise until the button comes out and the indicator shows that the circuit-breaker is in the CONNECT position. 5 – Extract the crank and place it in its housing. Rack out repeat the steps for rack in just in reverse order.
What type of transition do we use for our generator transfers? Explain the transition
Open Transition, open the MCBU breaker then close the MCBG breaker so that two different power sources do not connect
What type of transition do we use for our UPS Maintenance Bypass transfers? Explain the transition
Closed Transition, Maintenance Bypass. Close the MBP breaker before opening the IOB breaker so that power is never disconnected to the load
