Chint DZ20Y-1250/3300-1250A

     Chint DZ20Y-1250/3300-1250A is a molded case circuit breaker (MCCB) specially designed for high-power power distribution systems. It is suitable for main circuit protection in industrial facilities, commercial buildings, and large-scale constructions.

I. Core Technical Parameters

1. Basic Specifications

Frame Current: 1250A, which refers to the maximum rated current of the release that the circuit breaker frame can accommodate.

Rated Current: 1250A, the current value that the circuit breaker can continuously and stably carry in actual operation.

Pole Number: 3P, applicable to three-phase five-wire or three-phase three-wire systems.

Breaking Capacity: 50kA (at AC400V), which enables quick interruption of short-circuit current to protect equipment safety. It should be noted that some third-party platforms indicate a breaking capacity of 38kA, which may be caused by differences in test standards or model suffixes. It is recommended to refer to Chint's official technical documents for the most accurate information.

2. Release and Protection Functions

Release Type: The code "3300" indicates a thermal-magnetic release, which has both overload long-time delay (thermal protection) and short-circuit instantaneous (magnetic protection) functions.

Protection Characteristics:

  Overload Protection: Triggered by the thermal deformation of a bimetallic strip, with an inverse time-delay characteristic (the operating time is inversely proportional to the degree of overload).

  Short-Circuit Protection: The electromagnetic release trips instantaneously when the short-circuit current reaches the set value (usually 10 times the rated current).

No Leakage Protection: There is no "L" suffix in the model, so it does not have residual current protection function. An additional residual current circuit breaker (such as the DZ20LE series) needs to be configured if leakage protection is required.

3. Electrical and Mechanical Performance

Rated Insulation Voltage: 800V, adaptable to complex power grid environments.

Operation Method: Manual operation, with the handle used to switch between closing, opening, and free tripping states.

Mechanical Life: Approximately 2,500 operations, meeting the needs of long-term and frequent operation.

II. Application Scenarios

1. Power Distribution Systems

- Used as the main incoming line circuit breaker in substations and distribution rooms to protect transformers and lower-level power distribution lines from overload and short-circuit damage.

- Suitable for the main switch of motor control centers (MCCs), cooperating with lower-level protective electrical devices to achieve selective tripping.

2. Industrial and Commercial Equipment

- Provides power protection for driving large motors (such as water pumps and air compressors) to prevent equipment damage caused by inrush current during motor startup.

- Used in the power supply circuits of high-power equipment such as welding machines and electric furnaces to provide short-circuit and overload protection.

3. Building Electrical Systems

- Serves as the low-voltage power distribution main switch in high-rise buildings or commercial complexes to ensure power supply reliability.

- Used in the main distribution boxes of temporary power supply sites (such as construction sites) to meet the requirements of high protection levels.

III. Installation and Selection Recommendations

1. Installation Requirements

Dimensional Parameters: For front-panel wiring, the external dimensions are approximately 407mm (length) × 210mm (width) × 122mm (height), and the mounting hole spacing is 375mm × 70mm. Sufficient space should be reserved.

Wiring Method: Front-panel wiring is supported. It is recommended to use copper cables with a cross-sectional area of 120-240mm² to ensure reliable contact.

Environmental Conditions: The operating temperature range is -5℃ to +40℃, and the humidity should be ≤95% (without condensation). Avoid use in environments with corrosive gases or dust.

2. Selection Notes

Upper and Lower-Level Coordination: The breaking capacity and setting current of the upper-level circuit breaker (e.g., at the incoming line end) should be greater than those of the lower-level one to achieve selective protection. For example, the upper-level can select DZ20J-1600/3300 (with a breaking capacity of 65kA).

Accessory Expansion: An shunt release (such as DZ20Y-1250 left shunt release, AC220V) can be added to realize remote control, or auxiliary contacts can be installed to feed back the switch state.

Alternative Options: If higher breaking capacity is required, Chint's NXM series (e.g., NXM-1250S with a breaking capacity of 70kA) can be considered.

IV. Maintenance and Safe Operation

1. Regular Inspection

Appearance Inspection: Check quarterly for cracks or ablation marks on the housing and ensure the handle operates flexibly.

Contact Detection: Use an infrared thermometer to monitor the temperature of the terminal blocks annually, ensuring it does not exceed 70℃ (temperature rise ≤40K).

Trip Test: Every 2-3 years, use special test equipment to verify the overload and short-circuit protection functions to avoid malfunction or failure to trip.

2. Fault Handling

Trip Cause Analysis: In case of tripping, first determine whether it is caused by overload (thermal trip) or short-circuit (magnetic trip) through trip indicators (such as handle position or auxiliary contact signals).

Reset Operation: After troubleshooting, the handle must first be switched to the "open" position (reclosing) before it can be closed again. Avoid forced direct closing to prevent secondary faults.

V. Market Price and Procurement Recommendations

1. Price Range

- For quotation reference, please contact via WhatsApp: 0086-13811255435. The unit price of DZ20Y-1250/3300-1250A ranges from 2,400 to 4,250 RMB. The price difference is mainly due to whether accessories (such as shunt releases) are included.

2. Procurement Notes

Certification Standards: Ensure the product complies with international standards such as GB14048.2 and IEC 60947-2, and avoid using counterfeit products from unauthorized channels.

Delivery Cycle: Regular models are available in stock. Customized configurations (such as special voltage or accessories) require a pre-order period of 2-4 weeks.

VI. Typical Application Cases

Power Distribution Transformation in a Steel Plant: The original circuit breaker frequently tripped due to insufficient breaking capacity. After replacing it with DZ20Y-1250/3300-1250A, the inrush current during the startup of the steelmaking furnace was successfully handled, and the system failure rate decreased by more than 90%.

Main Incoming Line Protection in a Commercial Complex: In the low-voltage distribution room of a 20-story office building, this circuit breaker cooperates with the lower-level NXB series circuit breakers to achieve three-level selective protection, ensuring the continuous power supply for critical loads such as fire-fighting systems and elevators.

Through the above analysis, users can select the product reasonably according to their actual needs and follow the installation and maintenance specifications to ensure the long-term stable operation of the system. For more detailed technical support, it is recommended to contact Chint Electric's technical service department directly or visit its official website to obtain the latest product manual.