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Electrical Equipment Assembly – Control Panels 電気機器組立て (Grade 2 theory) sample exam questions – 10 questions with answers
技能検定「電気機器組立て」2級 学科（配電盤・制御盤組立て）
10 sample questions in the real exam format, with furigana, English translation, answers and explanations. Tap "Show answer" under each question. For the full question bank and realistic mock exams, open the free app.
Question 1
日本電機工業会規格（JEM）によれば、配電盤・制御盤の外形寸法を表す順序は、幅（W）、高さ（H）、奥行き（D）とされ、その数値にはつりボルト（アイボルト）や屋根上の換気装置の高さは含めない。
According to the Standards of the Japan Electrical Manufacturers' Association (JEM), the external dimensions of switchboards and control panels are expressed in the order of Width (W), Height (H), and Depth (D), and these figures exclude the height of lifting eye bolts or roof-mounted ventilation devices.
- A. ○
○ True - B. ×
× False
Show answer
Correct answer: A
True. Under JEM 1425, the nominal external dimensions of switchboards and control panels are specified in the order Width (W), Height (H), and Depth (D) in millimeters, excluding protruding parts such as lifting eye bolts and roof ventilators.
| Word | Meaning |
|---|---|
| 外形寸法 | external dimensions (gaikei sunpō) |
| つりボルト（アイボルト） | lifting eye bolt |
| 換気装置 | ventilation device |
Question 2
日本電機工業会規格（JEM）によれば、垂直自立形の配電盤・制御盤の外面及び監視用計器の縁の標準塗装色は、マンセル記号「5Y7/1」とされている。
According to the Standards of the Japan Electrical Manufacturers' Association (JEM), the standard paint color for the exterior surfaces of vertical freestanding switchboards and control panels and the bezels of panel-mounted monitoring instruments is Munsell notation '5Y7/1'.
- A. ○
○ True - B. ×
× False
Show answer
Correct answer: A
True. Under JEM 1425 and JEM 1135, the standard exterior paint color for switchboards, control panels, and instrument bezels is light yellowish gray, designated as Munsell 5Y7/1.
| Word | Meaning |
|---|---|
| 垂直自立形 | vertical freestanding type |
| 標準塗装色 | standard paint color |
| マンセル記号 | Munsell notation |
Question 3
三相誘導電動機の回転方向を逆転させるには、電源の3本の接続線（R・S・T相）のうち、すべての3本を順次入れ替えて接続しなければならない。
To reverse the direction of rotation of a three-phase induction motor, all three power supply leads (phases R, S, and T) must be cyclically interchanged and reconnected.
- A. ○
○ True - B. ×
× False
Show answer
Correct answer: B
False. Reversing the direction of the rotating magnetic field and the rotation of a three-phase induction motor requires interchanging any two of the three power supply leads (for example, swapping R and T while keeping S unchanged). Cyclically shifting all three leads preserves the same phase sequence.
| Word | Meaning |
|---|---|
| 三相誘導電動機 | three-phase induction motor |
| 回転方向の逆転 | reversal of rotation direction |
| 回転磁界 | rotating magnetic field |
Question 4
ホイートストンブリッジ回路において、検流計に電流が全く流れない平衡状態にあるとき、向かい合う2辺の抵抗値の和は互いに等しくなる。
In a Wheatstone bridge circuit, when the bridge is in a balanced state with zero current flowing through the galvanometer, the sum of the resistances of two opposite arms is equal to that of the other two opposite arms.
- A. ○
○ True - B. ×
× False
Show answer
Correct answer: B
False. The balance condition of a Wheatstone bridge is that the products (not the sums) of the resistances of opposite arms are equal: R₁ × R₄ = R₂ × R₃.
| Word | Meaning |
|---|---|
| ホイートストンブリッジ回路 | Wheatstone bridge circuit |
| 検流計 | galvanometer |
| 平衡状態 | balanced state |
Question 5
日本産業規格（JIS B 0001）の機械製図に規定する第三角法では、対象物を正面から見た正面図を中心として、上側から見た平面図を正面図の上方に、右側から見た右側面図を正面図の右側に配置する。
In third-angle projection specified by the Japanese Industrial Standards for mechanical drawing (JIS B 0001), with the front view at the center, the top view (plan view) is placed above the front view and the right side view is placed to the right of the front view.
- A. ○
○ True - B. ×
× False
Show answer
Correct answer: A
True. In third-angle projection (JIS B 0001), the top view is arranged directly above the front view, the right side view is placed to the right of the front view, and the left side view is placed to the left.
| Word | Meaning |
|---|---|
| 第三角法 | third-angle projection |
| 正面図と平面図 | front view and top (plan) view |
| 右側面図 | right side view |
Question 6
図に示す手動圧着工具（JIS C 9711）を用いて銅線用裸圧着端子を電線に圧着接続する作業に関する記述のうち、誤っているものはどれか。
Which of the following statements regarding crimping bare copper crimp terminals onto wires using the hand crimping tool (JIS C 9711) shown in the figure is INCORRECT?
- A. 圧着端子の公称断面積の呼びに合致した成形確認機構（ラチェット機構）付きのダイス溝を選定して圧着する。
Select the die groove equipped with a full-cycle ratchet mechanism that matches the nominal cross-sectional area designation of the crimp terminal. - B. 電線の絶縁被覆をむいた際、心線の先端が端子の電線抱き部（筒部）から1mm〜2mm程度突き出るように差し込む。
After stripping the wire insulation, insert the conductor so that the tip of the core strands protrudes about 1 mm to 2 mm from the terminal barrel. - C. 端子を仮押さえするときは、ハンドルを途中まで握った状態でそのままハンドルを開いて取り外す。
When you want to lightly pre-hold a stiff terminal, squeeze the handles halfway and immediately open them back up to remove the terminal. - D. 圧着作業完了後は、端子の筒部裏面に刻まれた圧着マーク（刻印）が使用した端子サイズと一致しているか確認する。
After completing the crimping operation, verify that the crimp mark embossed on the back of the terminal barrel matches the terminal size used.
Show answer
Correct answer: C
A hand crimping tool conforming to JIS C 9711 incorporates a ratchet (full-cycle) mechanism that prevents the handles from opening until the handles are squeezed all the way to completion, preventing incomplete crimps. The other three statements describe proper crimping procedures.
| Word | Meaning |
|---|---|
| 手動圧着工具 | hand crimping tool |
| 成形確認機構（ラチェット機構） | full-cycle ratchet mechanism |
| 圧着マーク（刻印） | crimp mark (embossed mark) |
Question 7
配電盤・制御盤の分類と構造に関する記述のうち、日本産業規格（JIS）及び日本電機工業会規格（JEM）に照らして、誤っているものはどれか。
Which of the following statements regarding the classification and construction of switchboards and control panels is INCORRECT according to JIS and JEM standards?
- A. コントロールセンタは、複数の電動機制御ユニットを多段積みに収容し、電動機群を一括管理する制御盤である。
A control center is a control assembly that houses multiple motor control units stacked in tiers for centralized management of a group of motors. - B. デスク形制御盤（DE-1形）の操作面の傾斜角度は、操作者の視認性と操作性を高めるため標準として15°とされている。
The standard inclination angle of the operating surface on a desk-type control panel (Type DE-1) is 15° to improve visibility and operability. - C. 屋外用配電盤の扉には、保守点検時に風などで扉が勝手に閉まらないよう扉止め（ドアストッパ）を設ける。
Doors on outdoor switchboards are provided with door stoppers to prevent them from closing accidentally due to wind during maintenance and inspection. - D. 垂直自立形制御盤の筐体は、外部からの衝撃にのみ耐えればよく、内部に取り付ける機器の重量は構造設計上考慮しない。
The enclosure of a vertical freestanding control panel only needs to withstand external impacts, and the weight of internally mounted equipment is not considered in structural design.
Show answer
Correct answer: D
Under JEM 1425, the enclosure and frame of a switchboard or control panel must be designed with sufficient mechanical strength to support the weight of all internally mounted equipment as well as operating and short-circuit forces.
| Word | Meaning |
|---|---|
| コントロールセンタ | control center (MCC) |
| デスク形制御盤 | desk-type control panel |
| 扉止め（ドアストッパ） | door stopper |
Question 8
極数4、定格周波数60Hzの三相誘導電動機が、すべりs ＝ 0.05（5%）で運転されているときの回転速度 N［min⁻¹］の値として、正しいものはどれか。
When a 4-pole, 60 Hz three-phase induction motor is operating at a slip of s = 0.05 (5%), what is the rotational speed N (min⁻¹)?
- A. 1425 min⁻¹
- B. 1710 min⁻¹
- C. 1750 min⁻¹
- D. 1800 min⁻¹
Show answer
Correct answer: B
The synchronous speed is Ns = (120 × f) / p = (120 × 60) / 4 = 1800 min⁻¹. At a slip s = 0.05, the actual rotor speed is N = Ns × (1 − s) = 1800 × (1 − 0.05) = 1710 min⁻¹.
| Word | Meaning |
|---|---|
| 同期速度 | synchronous speed |
| すべり（スリップ） | slip |
| 回転速度 | rotational speed |
Question 9
抵抗 R₁ ＝ 12Ω と抵抗 R₂ ＝ 6Ω を並列に接続し、これに抵抗 R₃ ＝ 6Ω を直列に接続した回路の両端に100Vの直流電圧を加えたとき、電源から流れ出る全電流 I［A］の値として、正しいものはどれか。
Resistors R₁ = 12 Ω and R₂ = 6 Ω are connected in parallel, and this parallel combination is connected in series with resistor R₃ = 6 Ω. When a DC voltage of 100 V is applied across the circuit, what is the total current I (A) flowing from the power supply?
- A. 10 A
- B. 12.5 A
- C. 4 A
- D. 25 A
Show answer
Correct answer: A
The equivalent resistance of the parallel branch is Rp = (12 × 6) / (12 + 6) = 72 / 18 = 4 Ω. Adding R₃ = 6 Ω in series gives a total resistance R = 4 + 6 = 10 Ω. By Ohm's law, the total current is I = 100 V / 10 Ω = 10 A.
| Word | Meaning |
|---|---|
| 直並列回路 | series-parallel circuit |
| 合成抵抗 | equivalent (combined) resistance |
| オームの法則 | Ohm's law |
Question 10
日本産業規格（JIS B 0021）の幾何公差表示方式において、データム（基準となる直線や平面）を必要としない「形状公差」に分類されるものの組み合わせとして、正しいものはどれか。
In geometrical tolerancing under JIS B 0021, which of the following combinations consists of 'form tolerances' that do NOT require a datum?
- A. 平行度 ― 直角度
Parallelism ― Perpendicularity - B. 真直度 ― 平面度
Straightness ― Flatness - C. 同軸度 ― 位置度
Coaxiality ― Position - D. 円周振れ ― 全振れ
Circular runout ― Total runout
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Correct answer: B
Under JIS B 0021, form tolerances include straightness, flatness, roundness, and cylindricity, none of which require a datum. Parallelism and perpendicularity are orientation tolerances; coaxiality and position are location tolerances; circular and total runout are runout tolerances—all of which require a datum.
| Word | Meaning |
|---|---|
| 幾何公差 | geometrical tolerance |
| 形状公差と姿勢公差 | form tolerance and orientation tolerance |
| データム（基準形体） | datum (reference feature) |