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Saudi ARAMCO STANDARDS > SAES-P-100 > Flashcards

SAES-P-100 Flashcards

(48 cards)

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1
Q

In Aramco LV distribution system , can Fuse and Circuit Breaker be used?

A

LV AC system circuit breaker should be used. Fuse cannot be used

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2
Q

When Fuse is allowed?

A

MCCB with integral current limiting fuses are permitted. FUSES are permitted for protection of circuits fed from UPS systemes

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3
Q

For Critical facilities? What type of switcgear arrangement should be used?

A

Secondary selective

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4
Q

What is primary distribution level and Secondary distribution level for SA ?

A

Primary is 13.8kV 3p,3W. Secondary is 4.16kV,3p,3w and 480V ,3P,3W.

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5
Q

Where 400V /230V level is only acceptable?

A

Sub distribution levels(general power supply inside buildings, distribution transformers to panel boards)

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6
Q

In SA,400Y/230V ,what grounding should be used?

A

Solid grounding

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7
Q

In SA 480V level requires what grounding?

A

Solid or high resistance grounded system. High resitance grounding is optional and restricted to critical facilities where service continuity is required

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8
Q

In SA , 4.16KV and 13.8kV level uses what grounding?

A

Low resistance grounding system . Exception: solid grounding system shall be specified for system feeding overhead lines.if system is feeding combination of overhead lines and other local loads , the system grounding design shall be selected so that the overhead line ground fault protection shall be capable of detecting 10-20% of the available ground fault current at the end of the overhead line

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9
Q

What will be the grounding system for generators connected directly to high voltage switchgear?

A

High resistance grounded system. An alternative ground fault source(grounding transformer) Shall be considered to meet the ground fault relaying sensitivity requiremnets when the system isoperating in island mode

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10
Q

What will be grounding system for voktage greater than 33kV?

A

Solid grounding system

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11
Q

When HVDC system is required in SA Facility?

A

For powering offshore projects with cable lengths greater than 75 kM or power requiremnt exceeding 100MW,hVDC shall be evaluated as a viable option. This evaluation shall be submitted to EED manager for concurrence

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12
Q

When we need to update existing ETAP model?

A

When adding a load rated less than 50HP or equivalent KVA does not require updating the electrical model. Exception: Adding a distribution equipment requires updating the electrical model and system studies regardless of the connected load size

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13
Q

What will be the grounding of generators connected to the low voltage switchgear?

A

Reactance grounded(effectively grounded) unless equipment short circuit duty requiremnets are met

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14
Q

What will be the grounding of generators connected to the low voltage switchgear?

A

Reactance grounded(effectively grounded) unless equipment short circuit duty requiremnets are met

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15
Q

How much should be the tap of off load transformer tap changer?

A

One or two steps off of the nuetral position.in this case, all studies shall use the same transformer tap postion

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16
Q

What will be the Tap of on load tap changers?

A

Position shall not exceed mid range(+5% or - 5% ) on the either side of the neutral position.however it is acceptable during normal voltage variations identified in SA grid code(+-5%) to temporarily reach the max range of the tap changer

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17
Q

What if the impedance of the transformers are not known from tests?

A

Impedance tolerance shall be used based on IEC 60076-1 for IEC TRF and ANSI/IEEE C57.12.00 for ANSI TRF

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18
Q

Explain Maximum Load Flow case?

A

All motors are off.
1) For secondary selective system: both incomers are closed and bus tie is open
2) for submarine cable application: one reactor shall be assumed out of service for submarine cables application
3) distribuition loop shall b3 assumed open at the furthest end in the circuit

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19
Q

Explain the minimum volatge conditions for load Flow?

A

1)One incomer out of service and bus tie is closed
2) operating load plus the largest (spare) motor if the spare motor is not interlocked to prevent starting while the primary motor is running
3)N-1 contigency

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20
Q

Are power factor caoacitor banks are considered in load Flow?

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A

No ,No to correct voktage drop nor to size any electrical equipment

21
Q

How the load should be modeled?

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A

Based on load schedule and metering data

22
Q

What should you do if you have metering data? What about global diversity factor?

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A

Diversity factor shall be applied to each downstream bus. Global diversity factor can only be used for sizing main equipment at receiving end substation .for sizing downstream equipment,specific load diversity factors shall be applied

23
Q

How should shunt reactors be sized?

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A

Shall be sized to maximize active power flow and to mitigate overvoltages resulting from feranti effect while maintaing steady state voktages

24
Q

What should be the short circuit duty percentage?

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A

Shall not be greater than 95% of corresponding bus and breaker

25
When motors should be lumped in short circuit study? What should FLA contribution?
Motors rated less 50HP can be lumped. 400% FLA short circuit contribution (sub transient reactance 25%) Shall be considered for LV motor load
26
How much is maximum allowable incident energy?
12 cal/cm 2
27
What is utility condition for motor starting study?
Maximum source impedance(minimum available short current at utility buses)
28
On which motors motor starting study need to be conducted?
1) Largest motor on each switchgear. If multiple switchgear are fed from the same source bus,then only one study for the largest motor amongst those switchgear is sufficient 2) largest motor on each control gear. If there are more than one control gear fed from same switchgear,then one study is sufficient for the largest motor among those control gears 3) when a new high voltage motors is added to the existing plant, the motor starting study requiremnets applies to both existing and new motors
29
When time domain motor starting study should be conducted?
1) when motor is 10000HP and greater 2) HV motors with restricted locked rotor current(lower than what is specified in API standards) regardless of motor size 3) During islanded condition,regardless of the size of the motor
30
Should PF correction capacitor bank should be connected during motor starting study?
No
31
When should be transient stability study shall be conducted?
For facilities with generation greater than 10MW or total motor loads addition greater than 10000HP to systemes with existing co generation plant
32
When harmonic analysis must be conducted?
For systems rated 400V and greater when the non linear load exceeds 10% of the supply transformer base rating.
33
Does frequency scan analysis should be done?
Yes ,in order to identify the potential harmonic resonance points
34
When and where base line harmonic measurement should be made?
1) should be conducted at bus and feeder where harmonics loads are added 2) should be conducted at each bus where a caoacitor bank to be added
35
What is the harmonic distortion limits?
At switchgear bus, voltage total harmonic distortion shall not exceed 5% and individual voktage harmonic distortion shall not exceed 3%
36
For offshore system, utilizing electrical submersible pumps with AFD? What type of filters must be used?how filters shall be sized?
High pass passive harmonic filters shall be installed at MV switchgear .filters shall be sized based on worst case operation scenario in terms of harmonic distortion
37
What are possible harmonic mitigation?
AFD line reactors, 18pulse(or greater )convertors, phase shifting transformers ,passive and active harmonic filter .
38
When K factor shall be considered?
For dry type Transformers feeding non linear load , including but not limited to ,lighting ,load K factor shall be calculated based on IEEE STD 1100. K rated transformer shall be specified when load K factor exceeds 1.0 Minimum K-13 rated dry type transformer can be used when harmonic data are not available
39
When power factor correction study need to be conducted?
If the load power factor at PCC is below 0.95% for maximum load flow(minimum voltage) scenario. PFC study need to be conducted to determine the reactive compensation device
40
How should be detuned filter shall be evaluated?
1) capacitor operating voltage, current, and kvar shall not exceed 100% of respective rated values under normal system operation 2)capacitor operating voltage, current, and kvar shall not exceed 110% of rated voltage, 135% of rated current and 135% of rated KVA respectively under system contigency operation 3) Reactor shall be sized to handle total rms current including harmonics plus 30% safety margin.current shall be based on calculated total filter currents including harmonics
41
What shall be steady state voltage variation upon switching capacitor bank?
Shall not exceed 3% and shall be asked with lowest system 3 phase short circuit MVA value
42
For capacitor bank application? When general purpose breaker or definite purpose circuit breaker shall be used?
Unless it is proven by switching transient study that the application of general purpose circuit breaker is adequate , capacitor bank shall be fed through a definite purpose caoacitor switching circuit breaker.
43
What are alternative power factor correction methods can be used?
Synchronous machine excitation and synchronous condesor utilization
44
What are the typical solution for mitigating sympathetic effects?
Transformer tap changer adjustments, demagnetisation of transformer core and point on wave switching
45
What are the typical solutions for mitigating ferroresonce ?
3 phase automatic interrupted, wye grounded /wye grounded transformers ,switchgear with voltage unbalance and over voltage relays 27/47
46
What is Basic switching level limit(BSL)?
98% Out of statistical switching for any switching operation should not exceed 80% of the BSL,but in no case shall exceed 100% of the BSL
47
What shall be Basic insulation level limit?
For both direct stroke and back falsh over events , the maximum determined over volatge at any equipment should not exceed 89% of the BIL of that equipment
48

Saudi ARAMCO STANDARDS (1 decks)

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