In-Depth Analysis of the Wiring Process for SIMO Motor 630KW High-Voltage Motor

In-Depth Analysis of the Wiring Process for SIMO Motor 630KW High-Voltage Motor

For high-voltage motors with a power rating of 630KW, the wiring process fundamentally differs from low-voltage systems. In high-voltage environments, insulation reliability, electrical clearance, and mechanical protection are the three core control points. Any minor oversight may lead to breakdown, discharge, or even short-circuit incidents. Below, we analyze common issues in high-voltage motor wiring from the professional perspective of Xi'an SIMO Motor.

Heat-Shrink Tubing vs. Tape:

For three-phase terminal connections (commonly known as "lugs"), color-coded heat-shrink tubing (e.g., yellow/green/red for phases A/B/C) is recommended instead of insulating tape. Heat-shrink tubing offers superior temperature resistance (typically above 125°C), insulation strength (above 2500V), and anti-aging performance, while color-coding facilitates future maintenance.

Cable entry and exit points must be tightly sealed with fireproof putty (e.g., organic sealing compound) to form a fire barrier. This prevents moisture ingress (high-voltage systems are sensitive to humidity), deters small animals from causing short circuits, and complies with fire safety regulations.

Excessive Length of AC Phase Cable Heads:

The current AC phase cable heads are excessively long, resulting in exposed conductors being too close to the metal casing of the junction box (insufficient safety clearance). It is advisable to precisely trim the cables based on actual wiring requirements (pre-layout simulation is recommended), retaining an appropriate margin (generally no more than 50mm) to avoid unnecessary cable accumulation.

The image shows the wiring of a 630KW high-voltage motor.

An excessively small bending radius can mechanically damage the insulation layer, leading to partial discharge over time. According to GB 50168-2018 Electrical Installation Engineering-Cable Line Construction and Acceptance Standards , the minimum bending radius for high-voltage cables should be no less than 15 times the cable diameter (for cross-linked polyethylene insulation). If space constraints exist, right-angle copper busbars can be installed to adjust connection angles and reduce bending stress.

Tin Plating for Terminals:

Contact surfaces between cable lugs and flat washers should undergo tin plating or tinning to prevent copper oxidation, which increases contact resistance (oxidation layers can raise resistance by 5-8 times). Silver-bearing solder (low melting point, high conductivity) is recommended to ensure smooth, burr-free contact surfaces.

Torque Tightening and Thermal Imaging Inspection:

Joints must be tightened with a torque wrench according to specifications (e.g., 44-54 N·m for M10 bolts). Before operation, infrared thermal imaging should be used to check temperature rise, ensuring that joint temperatures do not exceed ambient temperature by more than 40K (per GB 755-2019 standards).

Unconnected Shielding Layer:

The metal shielding layer of high-voltage cables must be reliably grounded (single- or double-ended grounding, depending on the system). Otherwise, induced voltage may breach the insulation. The correct method involves connecting the shielding layer to the motor casing via a grounding terminal, with grounding resistance below 4Ω and a conductor cross-section of at least 25mm² (copper).

Flexible Conduit and Insulating Sleeves:

For exposed cable sections between ground conduits and junction boxes, flexible metal conduits (e.g., galvanized) should be installed to prevent mechanical damage, along with insulating sleeves (e.g., silicone rubber) to cover exposed conductors. Ensure electrical clearance ≥125mm (standard for 10kV systems).

Exposed Primary Insulation Risk:

During cable termination, the primary insulation stripping length must strictly follow process requirements (typically the crimping length + 10mm) to avoid excessive conductor exposure. If insulation damage occurs, repair with high-voltage self-adhesive tape (e.g., 3M #23) in multiple layers, ensuring thickness ≥ original insulation.

1.Pre-Construction Preparation:

Verify cable specifications (voltage rating, cross-section) against motor nameplate data.

Use a cable phase tester to confirm phase sequence and avoid errors.

Prepare specialized tools: cable strippers, crimping tools, heat guns, insulation resistance testers.

2.Key Process Steps:

Strip cable outer sheath → Solder shielding layer ground wire → Crimp terminal → Shrink insulation tubing → Install phase-color sleeves → Conduct withstand voltage test (recommended: 2.5U₀ DC test for 15 minutes).

3.Acceptance Criteria:

Insulation resistance ≥1000MΩ (measured with a 2500V megohmmeter).

Clear phase identification and reliable grounding.

Electrical clearance and creepage distance comply with GB 14711-2013 General Safety Requirements for Small and Medium Rotating Electrical Machines .

The primary issues in this wiring project concern process standardization and protection integrity, particularly in AC phase treatment, shielding grounding, and mechanical protection, which require immediate rectification. As critical industrial equipment, high-voltage motor wiring must follow the principle of "precision and insulation priority." It is recommended that certified high-voltage electricians perform the work, with documented construction records and test reports to ensure long-term operational safety.

Discussion Topic:

What typical issues have you encountered in high-voltage equipment wiring? Share your experiences with SIMO Motor technicians and explore solutions together!