Zone Test Trips
Transformer Protecton
Other
Basic Power System
NMI Questions
100
How often is it necessary to perform a zone test trip?
Once every two years.
100
For a standard Hydro-One 230kV to 44kV transformation the secondary voltage lags the primary by _____ degrees
0 Degrees
100
The Breaker and half bus configuration is not often used in Hydro-One. True/False?
False-The breaker and half bus configuration is one of the most common switchyard arrangements used in Hydro One.
100
Who is the largest producer of power in Ontario?
OPG
100
What is the protocol if a SF6 Gas Density alarm received and low SF6 tank temperature alarm are sustained?
The equipment shall promptly be removed from service
200
It is required to perform ____ “live” test trip(s) when performing a scheduled routine zone test trip.
One
200
For a standard Hydro-One 115kV to 28kV transformation the secondary voltage lags the primary by _____ degrees.
What is 30 degrees
200
The ________ is an instrument field device used to accurately measure power system telemetry.
Transducer
200
Hydro One is the Crown Corporation that transmits the power to meet the needs of_____% of the population of Ontario. a) 50% b) 60% c) 90 % d) 80%
90%
200
What is the protocol if you receive an SF6 Gas Density alarm and the apparatus in alarm cannot be readily identified?
Immediate dispatch of Station Maintenance staff to identify the apparatus in alarm
300
What protection elements require zone test tripping? a) H.V. Power Transformers b) High Voltage Buses c) High Voltage Lines d) All of the above
All of the above
300
Restricted Ground Fault Protection for an In-Zone ground source is not required if adequately rated CT’s are available for the ground backup. True/False?
False
300
Which is the least expensive Switchyard Bus Configuration?
Single or Radial Fed
300
The 10% of customers not served by Hydro One are concentrated in which two areas?
Niagara and Sault Saint Marie
300
Evidence of an open-circuit fault could be:
1. Customer complaints of low or abnormal voltage. 2. Feeder ammeters on NMS indicate abnormally unbalanced phase currents. 3. Abnormally unbalanced voltages at distribution, municipal or customer-owned stations.
400
When in the protection re-verification process is the zone test trip performed? a) At the beginning before relay calibration checks. b) At the end of the protection testing but before load cross readings. c) At the end of protection testing and after load cross readings. d) It doesn’t matter.
At the end of protection testing and after load cross readings.
400
Transformer Master Ground Protection supervises the following LV Bus ground Relays and Lv Feeder Ground Relays. True/False?
True
400
How many Current Transformers are there in a typical Frame Leakage protection scheme?
Two .-One for the breaker ground strap and one for the current transformer ground strap.
400
What is an advantage to using AC over DC?
Large electrical generators happen to generate AC naturally, so conversion to DC would involve an extra step. Transformers must have alternating current to operate, and we will see that the power distribution grid depends on transformers. It is easy to convert AC to DC but expensive to convert DC to AC, so if you were going to pick one or the other AC would be the better choice.
400
Operating Networks may also implement voltage reduction (3% or 5%) locally when required for its own demand control reasons (i.e. equipment limitations). What is the protocol?
The IESO must be notified promptly, as per the voltage reduction SCO. Customers on the exclusion list are exempted.
500
Test tripping shall be preformed as required to complete protection verification. There is no requirement for equipment isolation during this testing. True/False?
True
500
The Brown Boveri type D2 transformer differential relay is a: a) constant slope differential relay b) variable slope differential relay c) fixed slope differential relay
Variable slope differential relay.
500
2. When is a Frame Leakage protection re-verification performed? a) After making wiring changes to the protection scheme. b) Six months after the installation of a new Frame Leakage protection. c) At maintenance intervals determined by Hydro One Networks and the schedulers. d) All of the above.
At maintenance intervals determined by Hydro One Networks and the schedulers.
500
Large scale blackouts occured in what 4 years?
1965, 1977, 1998 and 2003.
500
Name two stations that are washed in the fall just prior to the contamination monitoring season.
Beach TS Birmingham TS Gage TS Kenilworth TS Preston TS Manby TS 115kV East Strachan TS Gerrard TS
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