H7

Question 1

List some equipment that can be housed in an emergency lighting unit

Answer 1

Secondary cell
Trickle charger
Battery voltage indicating light
Test switch
Transfer relay
Voltage sensing equipment
Battery discharged disconnect switch

Question 2

What is meant by brownout protection for unit equipment?

Answer 2

Lights will transfer to the battery bank when a voltage dip of sufficient magnitude and duration occurs

Question 3

Which type of batteries are used with unit equipment?

Answer 3

Usually lead-acid and lead-acid gel cells or ni-cad

Question 4

Who has the authority or jurisdiction of emergency and exit installations?

Answer 4

CEC - general wiring of installation
NBC - governs where equipment is required

Question 5

Briefly describe standby power supply

Answer 5

A reliable source of power that is available either automatically or manually to maintain current supply to essential loads

Question 6

List four different places that commonly use a standby power supply

Answer 6

Hospitals
Schools
Airports
Shopping centers

Question 7

Name two types of prime movers commonly used in standby power systems

Answer 7

Combustion engines (gas, diesel, propane, natural gas)
Turbines (jet engine)

Question 8

What type of additional controls are required when standby power systems require parallel connection to other generator sets?

Answer 8

Synchronization controls must be in place to parallel the two sources

Question 9

What are the two basic types of transfer switches?

Answer 9

Manual and automatic

Question 10

List the six functions the ATS must be able to perform in its operation

Answer 10

1) Sense normal voltage and frequency
2) Start prime mover
3) monitor voltage and frequency of emergency power
4) transfer from normal power to emergency power
5) transfer from emergency power to normal power
6) ignore momentary power fluctuations

Question 11

What type of interlocking is associated with an ATS?

Answer 11

Break before make

Question 12

List the typical current ratings of available transfer switches

Answer 12

30A, 60A, 100A, 225A, 400A, 600A, 1000A

Question 13

List the ten basic steps of operation for an ATS

Answer 13

1) recognize loss of normal power
2) prevent switching during a short duration bump
3) start prime mover
4) recognize acceptable voltage and frequency of prime mover
5) transfer to emergency power
6) recognize return of normal power
7) transfer back to normal power after preset delay
8) allow prime mover to continue to run for preset time allowing engine cool down
9) provide positive interlocking between systems
10) provide trip free overcurrent protection as transfer switch may be closing on a fault

Question 14

What are the two safety hazards associated with an ATS?

Answer 14

Electrical hazards from the two sources
Mechanical hazard from the prime mover and transfer linkage

Question 15

List the purposes of plant exercising

Answer 15

1) prove operation of power plant (run loaded)
2) use up fuel before its stale
3) replace evaporated fuel (carburetor)
4) warm up and lubricate all engine parts
5) dispel any moisture
6) fully charge batteries

Question 16

Typically how often should ‘plant exercising’ be performed?

Answer 16

Once a week for 30 minutes

Question 17

Before performing any maintenance on an emergency generator set, what can to be done ensure unintentional starting will not occur?

Answer 17

Put transfer switch control to stop
Put genset control to stop
Open genset circuit breaker
DISCONNECT BATTERY

Question 18

What are UPS systems usually used for?

Answer 18

Provide backup power to critical loads
Provides power conditioning to sensitive loads

Question 19

What is an inverter?

Answer 19

Takes a DC voltage and inverts it to create an AC wave form

Question 20

What is the main reason inverters were developed?

Answer 20

They are more reliable and efficient than providing backup with a DC drive motor and an alternator

Question 21

There are many inverter types, but they all control the output frequency to the AC load the same way. How is this accomplished?

Answer 21

Solid state circuitry controls the timing of the firing of the SCRs or the transistors to produce an appropriate frequency

Question 22

What are the two main classifications of UPS systems?

Answer 22

Online and offline

Question 23

What is the difference between the two classifications of UPS systems?

Answer 23

Online: zero transfer time as the charger, batteries and inverter are always supplying the load
Offline: short transfer time as the static transfer switch goes from normal power to battery and inverter supplying the load