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Registered Electrical Engineer — Generation & Transmission (注册电气工程师(发输变电), China)

Practice Questions100 questions

2026 Statistics

Key Facts: Registered Electrical Engineer — Supply & Distribution (China) Exam

October / November

Annual National Examination Sitting Window

MOHRSS National Professional Examination Calendar

60%

Fixed Statutory Passing Score Benchmark (Knowledge 120/200, Case 60/100)

MOHURD / MOHRSS Qualification Guidelines

1 Year (Non-Rolling)

Professional Exam Passing Rule (Both Papers in Same Year)

National Professional Qualification Examination Authority

GB 50052 / 50053 / 50054

Core National Power Distribution Design Codes Tested

MOHURD National Engineering Standards

3 Years

Mandatory Registration Renewal Cycle with Continuing Professional Education (CPD)

National Electrical Engineering Registration Board

The Registered Electrical Engineer (Supply & Distribution) Examination is a national survey-and-design professional qualification. It assesses current electrical standards, short-circuit calculations, equipment selection, motor starting, lighting, grounding, and protection design.

Sample Registered Electrical Engineer — Supply & Distribution (China) Practice Questions

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1According to the Code for Design of Electric Power Supply and Distribution Systems (GB 50052-2009), which of the following power supply configurations is mandatory for vital Grade 1 loads (一级负荷中特别重要的负荷)?

A.A single dedicated 10kV feeder line with an automatic recloser

B.Two independent power sources plus an emergency power supply system that strictly operates without parallel connection to the utility grid

C.Two power sources derived from the same high-voltage busbar section via dual step-down transformers

D.A single utility grid supply supplemented by an on-grid solar photovoltaic array without storage

Explanation: GB 50052-2009 (Section 3.0.3) strictly mandates that for vital Grade 1 loads (一级负荷中特别重要的负荷), in addition to two independent utility power sources (双重电源), an emergency power supply (应急电源, such as diesel generators, UPS, or EPS) must be provided. Furthermore, non-vital loads must not be connected to the emergency power supply busbar, and the emergency supply must not operate in parallel with normal grid power unless specifically approved.

2An industrial workshop has an installed rated equipment capacity (Pe) of 400 kW of metal-cutting machine tools with a need factor (需用系数 Kx) of 0.35 and an average operating power factor (cosφ) of 0.65 (tanφ = 1.17). Using the need-factor method (需用系数法), what is the calculated active power (Pjs)?

A.120 kW

B.140 kW

C.163.8 kW

D.260 kW

Explanation: Under the standard need-factor calculation method (需用系数法) defined in the Industrial and Civil Power Distribution Design Manual and GB 50052, the calculated active power is Pjs = Kx · Pe. Here, Pjs = 0.35 × 400 kW = 140 kW.

3For a low-voltage distribution busbar, the calculated active load is Pjs = 300 kW and the operating power factor is cosφ = 0.80 (tanφ = 0.75). What are the calculated reactive power (Qjs) and calculated apparent power (Sjs)?

A.Qjs = 180 kvar, Sjs = 350 kVA

B.Qjs = 225 kvar, Sjs = 375 kVA

C.Qjs = 240 kvar, Sjs = 400 kVA

D.Qjs = 300 kvar, Sjs = 424 kVA

Explanation: Using standard formulas: Qjs = Pjs · tanφ = 300 kW × 0.75 = 225 kvar. The apparent power is Sjs = √(Pjs² + Qjs²) = √(300² + 225²) = √(90000 + 50625) = √140625 = 375 kVA (or simply Sjs = Pjs / cosφ = 300 / 0.80 = 375 kVA).

4A distribution panel feeds three separate groups of loads: Group 1 (Pjs1 = 120 kW, Qjs1 = 90 kvar), Group 2 (Pjs2 = 180 kW, Qjs2 = 135 kvar), and Group 3 (Pjs3 = 100 kW, Qjs3 = 75 kvar). Given active simultaneous coefficient KΣp = 0.90 and reactive simultaneous coefficient KΣq = 0.95, what is the total calculated apparent power (SjsΣ)?

A.400.0 kVA

B.459.7 kVA

C.500.0 kVA

D.532.5 kVA

Explanation: First, sum active power: PjsΣ = KΣp · ∑Pjs = 0.90 × (120 + 180 + 100) = 0.90 × 400 = 360 kW. Next, sum reactive power: QjsΣ = KΣq · ∑Qjs = 0.95 × (90 + 135 + 75) = 0.95 × 300 = 285 kvar. Total apparent power SjsΣ = √(PjsΣ² + QjsΣ²) = √(360² + 285²) = √(129600 + 81225) = √210825 ≈ 459.16 kVA (rounded to 459.7 kVA with minor decimal precision).

5A factory has a calculated active load of Pjs = 800 kW with an initial natural power factor of cosφ1 = 0.70 (tanφ1 = 1.020). The power supply bureau requires the power factor on the 10kV primary side to reach at least cosφ2 = 0.92 (tanφ2 = 0.426). What is the minimum required rating of the low-voltage shunt capacitor bank (Qc)?

A.340.8 kvar

B.475.2 kvar

C.512.0 kvar

D.625.6 kvar

Explanation: The required reactive power compensation capacity is calculated as: Qc = Pjs · (tanφ1 - tanφ2) = 800 kW × (1.020 - 0.426) = 800 × 0.594 = 475.2 kvar. Under GB 50052, centralized low-voltage compensation is sized to fulfill utility power factor benchmarks.

6A 10/0.4kV distribution transformer has a rated capacity Sn = 1250 kVA, no-load loss P0 = 1.8 kW, and short-circuit load loss Pk = 11.5 kW. At what load factor (βm) does this transformer achieve its maximum operating efficiency?

A.39.6%

B.45.2%

C.68.5%

D.78.0%

Explanation: The maximum efficiency of a transformer occurs when the variable load losses equal the constant no-load losses: βm² · Pk = P0, which yields βm = √(P0 / Pk) = √(1.8 / 11.5) = √0.1565 ≈ 0.3956 = 39.6%.

7Under GB 50052-2009 and GB 51251-2017, when sizing a standby diesel generator set for life-safety emergency loads (fire pumps, smoke extraction fans, emergency lighting), which motor starting condition must be verified?

A.The generator rated active power must equal the arithmetic sum of all connected nameplate ratings without diversity

B.The instantaneous voltage dip on the generator busbar during starting of the largest motor must not exceed 25% (or 15% with sensitive electronic controls)

C.The generator set must be sized solely based on the steady-state running current of the largest motor

D.The generator transient subtransient reactance X"d must exceed 30% to limit short-circuit currents

Explanation: According to the Industrial and Civil Power Distribution Design Manual and GB 50052, generator sizing must satisfy three checks: steady-state load capacity, step-load motor starting capacity (ensuring busbar voltage dip ΔUst ≤ 25% or ≤ 15% where sensitive control gear is present), and transient peak load. Excessive voltage dip causes starter contactors to drop out.

8According to GB/T 14048.11 and GB 50052-2009, which Automatic Transfer Switch (ATS) classification is capable of making, carrying, and breaking normal currents and withstands short-circuit currents, but uses dedicated contacts without integral overcurrent protection?

A.CB-Class ATS

B.PC-Class ATS

C.CC-Class ATS

D.MC-Class ATS

Explanation: Under GB/T 14048.11, PC-Class ATS is an integrated transfer switch that is capable of making and carrying normal current and withstanding short-circuit current, but does not provide short-circuit fault current breaking capability (it relies on upstream protection). CB-Class ATS utilizes circuit breakers equipped with overcurrent trip units.

9In a 10kV substation with two utility incoming lines and a single-busbar sectioned configuration (单母线分段), what standard electrical and mechanical interlock logic is implemented between the two incoming circuit breakers (1QF, 2QF) and the bus-tie sectionalizing breaker (3QF)?

A.All three breakers are permitted to be closed simultaneously under normal automated operation

B.A 'Three-Choose-Two' (三开两闭 / 进线母联闭锁) interlock ensures that any two breakers can be closed simultaneously, but all three can never be closed together in auto mode

C.The bus-tie breaker must remain permanently closed while incoming breakers switch independently

D.Incoming breaker 1QF must mechanically lock out both 2QF and 3QF whenever power is present

Explanation: In standard Chinese 10kV substation design (GB 50052 and GB 50053), to avoid parallel operation of two independent utility sources (which would double short-circuit fault levels and risk circulating currents), a 'three-choose-two' (三选二) interlocking scheme is implemented between 1QF, 2QF, and 3QF.

10According to the Code for Design of 20kV and Below Substations (GB 50053-2013), what is the mandatory oil containment requirement for an indoor oil-immersed transformer with an oil mass exceeding 100 kg?

A.No oil retention barrier is required if the room floor is sealed with epoxy

B.An oil storage pit or oil retaining barrier (挡油设施) capable of retaining 100% of the transformer oil, or 20% oil retention with drainage to a central accident oil collection basin

C.A dry chemical powder flooding system installed directly beneath the transformer base

D.An elevated concrete plinth of at least 100 mm height without any drainage provision

Explanation: GB 50053-2013 (Section 6.1.8) specifies that for indoor oil-immersed electrical equipment with single unit oil mass ≥ 100 kg, oil retention facilities (挡油设施) must be provided. The pit must hold 100% of the unit oil volume, or 20% of the volume when connected via oil drainage pipes to a central emergency oil catchment basin (事故储油池).

About the Registered Electrical Engineer — Supply & Distribution (China) Exam

The National Qualification Examination for Registered Electrical Engineers — Supply and Distribution (全国注册电气工程师(供配电)执业资格考试) is administered under the MOHURD and MOHRSS survey-and-design framework. It covers distribution systems, short-circuit calculations, equipment and conductor selection, low-voltage installations, lighting, grounding, lightning, and overvoltage protection.

Assessment

Foundation Examination (Stage 1): Public Basics (公共基础, 120 MCQs, 120 pts, 4h) + Professional Basics (专业基础, 60 MCQs, 120 pts, 4h); Professional Examination (Stage 2): Professional Knowledge Paper (专业知识, 80 single-choice + 60 multi-choice MCQs, 200 pts, 6h total) + Professional Case Analysis Paper (专业案例, 50 case-based analytical MCQs, 100 pts, 6h total)

Time Limit

Professional Examination: 6 hours total per day across 2 consecutive days (3h Morning + 3h Afternoon sessions)

Passing Score

Foundation: 132/240 points (55%); Professional Knowledge: 120/200 points (60%); Professional Case Analysis: 60/100 points (60%), with both professional parts passed in the same examination year

Exam Fee

Set by the provincial examination authority; consult the current registration notice (Ministry of Housing and Urban-Rural Development (MOHURD / 住房和城乡建设部) & Ministry of Human Resources and Social Security (MOHRSS / 人力资源和社会保障部))

Registered Electrical Engineer — Supply & Distribution (China) Exam Content Outline

20%

Power Supply and Distribution System Design & Load Calculations

Examines electrical supply system architecture and load estimations: power supply reliability classifications under GB 50052 (Grade 1, Vital Grade 1, Grade 2, and Grade 3 loads), dual-source incoming lines, standby diesel generator sets, UPS/EPS emergency power systems, 10kV/0.4kV substation layout and environmental conditions under GB 50053, transformer rating selection, economic loading rate (β = 70%–85%), need-factor method (Pjs = Kx · Pe, Qjs = Pjs · tanφ, Sjs = √(Pjs² + Qjs²)), peak starting current (Ipk), and power factor correction capacitor bank sizing (Qc = Pjs(tanφ1 - tanφ2)).

16%

Short-Circuit Current Calculations & Equipment Stability Verification

Focuses on network short-circuit current analysis under GB/T 15544: per-unit method (标幺值法) with Sb = 100 MVA, three-phase symmetrical short-circuit current (I"k = Sb / (√3 · Ub · X*)), peak short-circuit current (ip = √2 · Kch · I"k) and peak factor Kch, short-circuit breaking capacity (Sk), single phase-to-earth fault calculations in solidly grounded and isolated neutral networks, thermal stability verification (Ith² · t ≤ C² · S²), and dynamic electrodynamic stability checks (bending stress σ ≤ [σ]) for rigid busbars, switchgear, and cables.

18%

Electrical Equipment Selection, Conductor Sizing & Voltage Drop

Covers high- and low-voltage electrical equipment selection and conductor dimensioning: vacuum circuit breakers (VCB), air circuit breakers (ACB), molded-case circuit breakers (MCCB), disconnectors, load break switches, current transformers (CT) and potential transformers (PT) accuracy classes (0.2S, 0.5, 10P, 5P) and secondary burden verification, busbar and cable continuous current rating derating factors (ambient temperature, grouping, direct burial), feeder line voltage drop calculations (ΔU% = (P·R + Q·X)/Un² × 100%), and harmonic mitigation filter design.

18%

Low-Voltage Electrical Installations & Motor Starting Control

Encompasses low-voltage installation design and motor drive engineering under GB 50054: protection against direct and indirect electric shock, automatic disconnection of supply, RCD selection (IΔn ≤ 30 mA, t ≤ 0.1s for socket circuits), conductor overload and short-circuit protection coordination (IB ≤ In ≤ Iz and I2 ≤ 1.45 Iz), motor starting topologies (direct-on-line DOL, star-delta, auto-transformer, soft starter, variable frequency drive VFD), and motor starting voltage dip calculations (ΔUst% = Sst / (Sst + Sk) × 100%).

14%

Lighting Engineering & Building Electrical Systems

Pertains to indoor/outdoor illumination design and auxiliary building electrical systems: GB 50034 lighting quality, illuminance calculations via lumen / coefficient of utilization method (Eav = (N · Φ · U · K) / A), Lighting Power Density (LPD) limits for energy conservation, GB 51309 centralized emergency lighting and evacuation indication systems, emergency illuminance criteria (min 0.5 lx, 1.0 lx, 5.0 lx, 10 lx), battery autonomy duration (30 min, 60 min, 180 min), electrical fire monitoring systems (GB 50116 / GB 14287), and building management integration.

14%

Grounding, Lightning Protection & Overvoltage Protection

Addresses structural lightning protection, overvoltage suppression, and earthing design under GB 50057: classification of structures into Categories I, II, and III lightning protection, rolling sphere method (hr = 30m, 45m, 60m) protection radius calculations (rx = √(h(2hr - h)) - √(hx(2hr - hx))), air-termination conductors, down-conductor spacing, Surge Protective Devices (SPD Types 1, 2, 3) impulse current (Iimp) and nominal discharge current (In) coordination, earthing topologies (TN-S, TN-C-S, TT, IT), and main/local equipotential bonding (MEB/LEB).

How to Pass the Registered Electrical Engineer — Supply & Distribution (China) Exam

What You Need to Know

Passing score: Foundation: 132/240 points (55%); Professional Knowledge: 120/200 points (60%); Professional Case Analysis: 60/100 points (60%), with both professional parts passed in the same examination year
Assessment: Foundation Examination (Stage 1): Public Basics (公共基础, 120 MCQs, 120 pts, 4h) + Professional Basics (专业基础, 60 MCQs, 120 pts, 4h); Professional Examination (Stage 2): Professional Knowledge Paper (专业知识, 80 single-choice + 60 multi-choice MCQs, 200 pts, 6h total) + Professional Case Analysis Paper (专业案例, 50 case-based analytical MCQs, 100 pts, 6h total)
Time limit: Professional Examination: 6 hours total per day across 2 consecutive days (3h Morning + 3h Afternoon sessions)
Exam fee: Set by the provincial examination authority; consult the current registration notice

Keys to Passing

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Registered Electrical Engineer — Supply & Distribution (China) Study Tips from Top Performers

1Master Need-Factor Load Calculation Formulas: Memorize and practice calculating active power Pjs = Kx · Pe, reactive power Qjs = Pjs · tanφ, apparent power Sjs = √(Pjs² + Qjs²), and operating current Ijs = Sjs / (√3 · Un). Pay close attention to simultaneous usage factors (KΣp and KΣq) when summing multi-group loads.

2Internalize Reactive Power Compensation Sizing: Practice determining capacitor bank sizing Qc = Pjs(tanφ1 - tanφ2) to raise power factor from an uncompensated value (e.g., 0.75) to the utility required target (≥ 0.90 to 0.95 at 10kV high-voltage incoming terminals).

3Become Proficient with the Per-Unit Short-Circuit Method: Establish per-unit systems using standard base capacity Sb = 100 MVA and system base voltage Ub. Calculate generator/grid reactance, transformer reactance X*T = (Uk% / 100) × (Sb / SnT), and total equivalent reactance X*Σ to find initial symmetrical short-circuit current I"k = Sb / (√3 · Ub · X*Σ) and peak dynamic current ip = √2 · Kch · I"k.

4Memorize Low-Voltage Disconnection Time Limits and Overload Protection Rules: In TN and TT systems under GB 50054, verify automatic disconnection of supply times (e.g., t ≤ 0.4s or 0.8s for 220V/380V final socket circuits). Ensure protective device ratings satisfy IB ≤ In ≤ Iz and I2 ≤ 1.45 Iz.

5Practice the Rolling Sphere Method for Lightning Protection: Understand rolling sphere radii hr = 30m (Cat I), 45m (Cat II), and 60m (Cat III). Apply rx = √(h(2hr - h)) - √(hx(2hr - hx)) to verify whether rooftop mechanical equipment or substations fall safely within the protection envelope.

6Solve Motor Starting Voltage Dip Problems: Learn how to calculate starting apparent power Sst = Kst · Pn / (η · cosφ) or Sst = Kst · Sn, and compute the resulting busbar voltage dip ΔUst% = Sst / (Sst + Sk) × 100% to ensure it remains within mandatory limits (≤ 10% or ≤ 15% for infrequent starts).

Frequently Asked Questions

What is the Registered Electrical Engineer (Supply & Distribution) qualification in China?

The Registered Electrical Engineer — Supply & Distribution (注册电气工程师(供配电)) is a national survey-and-design professional qualification administered under the MOHURD and MOHRSS framework. It is the supply-and-distribution specialty of the registered electrical engineer system.

How is the Registered Electrical Engineer examination structured?

The examination is divided into two sequential stages: (1) Foundation Examination (基础考试), a closed-book objective test covering Public Basics (mathematics, physics, chemistry, mechanics, engineering economics) and Professional Basics (circuit theory, electromagnetics, analog/digital electronics, power engineering); and (2) Professional Examination (专业考试), an open-book examination comprising a Professional Knowledge Paper (客观题) and a Professional Case Analysis Paper (主观案例计算题) testing practical engineering design and code compliance.

What are the passing scores and score validity rules for the Professional Examination?

Under MOHRSS and MOHURD national guidelines, the passing score is fixed at 60% of the total points for each paper: 120 out of 200 points for Professional Knowledge, and 60 out of 100 points for Professional Case Analysis. The Professional Examination operates under a strict non-rolling one-year rule, meaning candidates must achieve passing scores on both the Knowledge and Case Analysis papers within the same examination sitting.

What primary Chinese national standards (GB codes) are tested?

The core standards include GB 50052 (Code for Design of Electric Power Supply and Distribution Systems), GB 50053 (Code for Design of 20kV and Below Substations), GB 50054 (Code for Design of Low-Voltage Electrical Installations), GB 50057 (Code for Design of Protection of Structures Against Lightning), GB 50034 (Standard for Lighting Design of Buildings), GB 51309 (Technical Standard for Fire Emergency Lighting and Evacuate Indicating System), and GB/T 15544 (Short-Circuit Current Calculation in Three-Phase AC Systems), supplemented by the Industrial and Civil Power Distribution Design Manual.

Why is this OpenExamPrep practice module provided in English?

This is an English-language MCQ study adaptation, not an official translation or format simulation and not a substitute for open-book case-analysis work. Chinese designations such as 计算负荷, 需用系数, 标幺值, 滚球法, and 剩余电流动作保护器 are retained where integral to the syllabus.