**Professional wiring guide for explosion-proof Roots blower**
---
**1、 Basic requirements for explosion-proof electrical systems**
1. Interpretation of Explosion proof Signs**
-Typical symbol: Ex d Ⅱ C T4 Gb
-Ex: Explosion proof certification
-* * d * *: Explosion proof type
-IIC: Suitable for hydrogen level hazardous environments
-T4: Surface temperature ≤ 135 ℃
-* * Gb * *: Equipment protection level (high-risk area)
2. * * Cable selection criteria**
|Parameters | Requirements|
|--------------------|-----------------------------|
|Cable type | CY type rubber sheathed cable/BNG explosion-proof steel pipe wiring|
|Cross section | Power line ≥ 2.5mm2, control line ≥ 1.5mm2|
|Color identification | Yellow green dual color grounding wire (cross-sectional area ≥ 50 phase line)|
---
**2、 Detailed explanation of wiring steps**
```mermaid
graph TB
A [power input] -->B [explosion-proof junction box]
B -->C [Explosion proof motor]
B -->D [Explosion proof control box]
D -->E [Ex d Certified Initiator]
```
1. * * Explosion proof junction box operation**
-Power off and detect combustible gas concentration (＜ 25LEL) before opening the lid
-Measurement of residual voltage using an intrinsic safety multimeter driven by CR2032 lithium battery
-Reference for tightening nut torque:
|Cable specifications | Torque value (N · m)|
|----------|--------------|
| M20×1.5 | 45±5 |
| M25×1.5 | 60±5 |
2. * * Motor terminal connection**
-Star Triangle Startup Wiring Specification:
```
U1-V1-W1： Power incoming line
U2-V2-W2： motor winding
Grounding terminal: independent grounding (resistance ≤ 4 Ω)
```
-Explosion proof sealing treatment:
-Use Ex certified cable sealing joints (such as CMP series)
-Inject explosion-proof adhesive (thickness ≥ 3mm)
3. * * Control circuit wiring**
-The distance between intrinsic safety circuits and non intrinsic safety circuits is ≥ 50mm
-Grid selection calculation:
$$
U_{max} \leq 0.7U_i \\
I_{max} \leq 0.7I_i
$$
(Ui/Ii is the rated value of the gate)
---
**3、 Key components of explosion-proof system**
|Components | Technical Requirements|
|--------------------|-------------------------------------------------------------------------|
|Explosion proof circuit breaker * * | Breaking capacity ≥ 10kA, with short circuit locking function|
|* * Positive pressure ventilation system * * | Maintain a pressure of ≥ 50Pa inside the box (requires interlocking control, automatically shuts off when the pressure is less than 25Pa)|
|* * Temperature Sensor * * | PT100 Platinum Resistance (Ex ia IIC T4 Certification)|
|Grounding system * * | Independent grounding electrode (galvanized flat steel 40 × 4mm), grounding resistance ≤ 4 Ω (humid environment ≤ 1 Ω)|
---
**4、 Typical wiring diagram example**
**Explosion proof motor direct starting scheme * *:
```plaintext
L1/L2/L3 → Explosion proof circuit breaker → Explosion proof contactor → Motor
↑ ↑
Emergency stop button ← Explosion proof control transformer (220V/24V)
```
**Interlocking requirements * *:
-Open lid power-off delay time ≤ 0.1 seconds
-The door switch must comply with the EN 60079-0 mechanical interlocking standard
---
**5、 Special working condition handling**
1. * * Application of frequency converter**
-Ex d type frequency converter (such as ABB ACS880-07) must be selected
-Install dv/dt filter at the output end (limited to<1000V/μ s)
-Cable length limit:
|Carrier frequency | allowable length|
|----------|------------|
| 4kHz | 150m |
| 8kHz | 75m |
2. * * Hazardous Area Classification**
-Zone 1: Adopting dual explosion-proof (explosion-proof+increased safety)
-Zone 2: Only Ex e increased safety junction boxes can be used
---
**6、 Testing and Certification**
1. * * On site inspection items**
-Insulation resistance: ≥ 100M Ω (measured with a 1000V megohmmeter)
-Loop resistance: phase to phase deviation ≤ 5
-Voltage withstand test: 2Un+1000V (lasting for 1 minute)
2. Verification of certification documents**
-Explosion proof certificate (CNEX/ATEX/IECEx)
-On site installation confirmation letter (signed by a qualified explosion-proof electrical engineer)
---
**7、 Common errors and corrections**
|Error phenomenon | Risk level | Rectification measures|
|--------------------|----------|---------------------------------|
|Sealing ring not tightened | Level II | Replace elastic sealing ring (compression capacity 30-40)|
|Grounding wire series connection | Level I | Change to star grounding (single point grounding)|
|Explosion proof surface scratch depth>0.1mm | Grade III | Mechanical polishing+rust proof oil treatment|
---
**Note: In a hydrogen environment (Class IIC), all wiring operations must use copper alloy tools (with a copper content of ≥ 60) to avoid mechanical sparks. It is recommended to conduct a special explosion-proof performance inspection every 6 months, with a focus on testing the gap between the explosion-proof joint surfaces (in accordance with GB 3836.2 standard).
