The power distribution cabinet with NH40SZ4P300A dual power supply is an electrical device specifically designed for scenarios requiring highreliability power supply. Its core function is to achieve automatic switching between two power sources to ensure the continuous operation of critical loads. The following elaborates on it from aspects such as technical parameters, functional features, application scenarios, installation and maintenance, etc.:
- Analysis of Core Parameters and Functions
- Model Definition
NH40SZ: It is a PCclass automatic transfer switch (ATSE) of CHINT Electric. Adopting the structure of a load isolating switch, it has the ability of rapid switching (about 100ms level) and is suitable for a threephase fourwire system.
4P: It has a fourpole design, which can control threephase phase lines and the neutral line simultaneously and support 380V/220V mixed loads.
300A: The rated current can meet the power consumption needs of small and mediumsized industrial equipment, commercial buildings or data centers.
- Technical Features
Power Switching Logic
Autotransfer and Autorecovery: When the main power source fails, it automatically switches to the standby power source, and automatically switches back when the main power source recovers (default mode).
Autotransfer without Autorecovery: After the main power source recovers, it needs to be manually switched back, which is suitable for scenarios where the standby power source is a generator.
Mutual Standby: There is no priority between the two power sources, and it automatically switches to the other one when either power source fails.
Protection FunctionsClick on the red text to view the
Overvoltage/undervoltage protection (the threshold can be set, for example, the switching is triggered when it exceeds 110% of the rated voltage or is lower than 80%).
Phase loss protection (switching occurs when any phase is detected to be missing).
Control Modes
Manual switching: Operated through the panel buttons or key switches.
Automatic switching: The builtin controller monitors the power status in realtime and supports remote control (external buttons or PLC signals are required).
- Performance Indicators
Rated Voltage: AC 380V (threephase) / 220V (singlephase).
Shortcircuit Withstand Current: The PCclass switch does not have the shortcircuit breaking capacity, but can withstand shortterm shortcircuit current (such as 50kA/1 second).
Mechanical Life: Approximately 12,000 times (switching without load).
Electrical Life: Approximately 1,000 times (switching with load).
- Application Scenarios
- Key Areas
Hospitals: Ensure the continuous power supply of equipment such as operating rooms, ICUs, and ventilators.
Data Centers: Support the dualchannel redundant power supply for servers and network devices.
Fire Protection Systems: Ensure the normal operation of fire pumps and emergency lighting during a fire.
Industrial Production Lines: Prevent production shutdown losses caused by power outages (such as in the chemical and food processing industries).
Transportation Hubs: The signal systems and ventilation equipment in highspeed railway stations and airports require stable power supply.
- Typical Loads
Motors: Attention should be paid to the starting current (it is recommended that the load current does not exceed 80% of the switch’s rated value).
Lighting Systems: Support nonlinear loads such as LED and fluorescent lamps.
Sensitive Electronic Equipment: A voltage stabilizer or UPS needs to be equipped to deal with voltage fluctuations.
III. Brand and Market References
- Brand Selection
CHNT: The NH40SZ series is a mainstream domestic model with high costeffectiveness and supports customized configurations (such as with auxiliary contacts and shunt trip devices).
Schneider (APC): The MT series dual power switch has a higher shortcircuit breaking capacity (such as 100kA) and is suitable for highend industrial scenarios.
ABB: The Tmax series ATSE supports intelligent monitoring and communication functions and is suitable for data centers.
- Price Range
CHNT NH40SZ4P300A: Approximately CNY WA：008613811255435 (including the controller and installation accessories).
Schneider MT 4P 320A: Approximately CNY WA：008613811255435.
ABB Tmax XT 4P 320A: Approximately CNY WA：008613811255435.
- Key Points of Installation and Maintenance
- Installation Requirements
Environmental Conditions:
Temperature: 5°C to +40°C, humidity ≤ 50% (at 40°C).
Altitude: ≤ 2,000 meters, without corrosive gases or dust.
Wiring Specifications:
Connect the main power source (Route I) to the front end of the switch, the standby power source (Route II) to the rear end, and the load to the outlet terminal.
The control circuit needs to be wired separately to avoid interference.
Grounding Requirements: The cabinet needs to be reliably grounded (the grounding resistance ≤ 4Ω).
- Maintenance Suggestions
Regular Inspections:
Clean the internal dust every quarter and check whether the wiring terminals are loose.
Test the switching function (it is recommended to conduct a loaded test) to ensure that the switching time ≤ 100ms.
Troubleshooting:
Switching Failure: Check whether the control power source is normal and whether the sensor is damaged.
Abnormal Heating: Check whether the load is overloaded and whether the contact points are oxidized.
- Certifications and Standards
Domestic Certifications:
3C Certification: Complies with the GB/T 14048.11 standard “Automatic Transfer Switching Equipment”.
Fire Protection Certification: Some models have passed the fire protection product certification (such as suitable for the power supply of fire pumps).
International Certifications:
CE Certification: Complies with the IEC 6094761 standard and can be exported to Europe.
UL Certification: Some models have passed the UL 1008 certification and are suitable for the North American market (customization is required).
- Considerations for Model Selection
- Load Type:
For motor loads, the starting current needs to be considered (it is recommended to select a switch with a rated current 1.5 times that of the load).
For nonlinear loads (such as UPS and frequency converters), the harmonic compatibility needs to be verified.
- Type of Standby Power Source:
When a generator is used as the standby power source, a delayed switching needs to be set (to avoid switching when the generator is not stable).
- Redundant Design:
In important scenarios, the “dual busbars + ATS” architecture can be adopted to achieve N+1 redundancy.
VII. Supplier Recommendations
Domestic: CHNT, Delixi, Nader.
International: Schneider, ABB, Siemens.
It is recommended to contact the supplier to obtain the detailed technical manual and customize the power distribution cabinet solution according to actual needs (such as adding surge protection, intelligent monitoring modules, etc.).
