POWER SYSTEM

How many and what types of substations are included in the Shah Alam Line's 132kV Bulk Supply System?

• 2 BSS, 1 SSU, 18 TPSS, 7 RS, 2 LVSS

• 3 BSS, 2 SSU, 16 TPSS, 5 RS, 3 LVSS

• 2 BSS, 1 SSU, 20 TPSS, 6 RS, 2 LVSS

• 1 BSS, 1 SSU, 18 TPSS, 7 RS, 2 LVSS

Under which condition will the No-Volt Automatic Changeover (NVAC) Scheme be initiated?

• When total power loss occurs at BSS or SSU

• During any minor voltage fluctuation in the 33kV system

• Under single failure condition of BSS equipment or outgoing feeder to 33kV network at BSS

• When power supply increases above 110% of nominal voltage

Answer explanation

The initiation of NVAC Scheme will only apply under single failure condition of BSS equipment, or outgoing

feeder to 33kV network at BSS to reduce the complexity and minimizing the operation risk.

Which of the following statements about the NVAC Scheme is true?

• NVAC will be triggered during total power loss at the BSS

• NVAC will automatically restore power through permanent genset

• NVAC operates through manually controlled switches only

• NVAC will not initiate if power drops below 50% for less than 3 seconds

Answer explanation

When incoming power supply drops below 50% of the nominal voltage for more than 3s, the NVAC shall be initiated.

(it will be coordinated so that NVAC will do the power restoration before permanent genset)

What is the main function of the Load Break Switch?

• To increase power supply

• 
  To monitor voltage levels

• To provide emergency power

• To connect or isolate two power rail sections

What happens when a BLS plunger is activated?

• It sends a wireless signal to the station operator for manual shutdown

• It energizes the 110V DC trip circuit to open the BLS door

• It cuts off the 110V DC trip circuit and triggers the BLRP to trip the DC Feeder Breaker

• It automatically resets the BLS and re-energizes the power rail

Answer explanation

Each activated BLS plunger will cut off 110V DC normally energized trip circuit. The trip circuit, comprising one BLS plunger, will be wired to the Blue Light Relay Panel (BLRP) at TPSS.

Which of the following signals are sent from the BLS to SCADA?

• BLS Temperature Alarm and BLS Maintenance Status

• BLS Tripping Signal and BLS Door Open

• BLS Reset Confirmation and BLS Voltage Status

• BLS Activation Timer and BLS Location Update

Answer explanation

Each BLS will send 2nos of IO signal to SCADA which are:
a) BLS Tripping Signal
b) BLS Door Open

What are the requirements that must be fulfilled in order to close a CIS?

• Bustie closed

• F1 and F2 closed

• F1 and F3 closed

• F2 and F4 closed

How many types of Traction Power Substations (TPSS) are there in the Shah Alam Line?

• 5

• 9

• 2

• 8

Answer explanation

2 types of TPSS:
a) with inverter ( TPSS03, TPSS05, TPSS08, TPSS10, TPSS12, TPSS15, TPSS18, TPSS23, TPSS DEPOT)
b) without inverter

Where is the Line Test Device (LTD) located?

• HSCB Rectifier Trolley Breaker

• HSCB Trolley Positive Breaker

• HSCB Trolley Negative Breaker

• CIS Trolley

How many types of HSCB (High-Speed Circuit Breaker) are there, and where are they located?

• 1 type – UR60 only, located at all HSCB breaker

• 2 types – UR40 at all feeder and inverter breaker, UR60 at rectifier breaker and bustie

• 2 types – UR40 at Rectifier breaker and bustie and UR60 at all feeder and inverter breaker

• 3 types – UR20, UR40, and UR60 at all feeder