What are the acceptance criteria for debugging the distribution box?
The acceptance criteria for distribution box/cabinet debugging should be based on national specifications, design drawings and industry requirements, covering core dimensions such as electrical performance, safety protection and function realization. The following are the main acceptance points based on GB 50171 "Standard for Construction and Acceptance of Wiring of Disks, Cabinets and Secondary Circuits in Electrical Equipment Installation Works" and other specifications:
A, electrical safety performance acceptance
1. Insulation and grounding
Insulation resistance:
The main circuit (phase-to-phase, relatively grounded) is ≥10MΩ (wet environment is ≥2MΩ), and the control circuit is ≥2MΩ (tested with a 500V megohmmeter, with test records attached).
Acceptance method: Spot check key circuits (such as main incoming line and high current circuit) and check the test report data.
Grounding system:
The PE line of the cabinet is firmly connected with the grounding terminal, and the grounding resistance is ≤4Ω (measured by grounding resistance tester); When multiple cabinets are side by side, the cross-sectional area of the jumper copper bar is ≥ 40 mm, and the equipotential connection is reliable.
Acceptance method: Visually check the grounding mark, cable color (yellow and green) and crimping process, and randomly check the grounding resistance test value.
2. Protection level
The sealing strip of the cabinet is complete, the door lock is tightly closed, and the protection level should meet the design requirements (such as IP30 for preventing solid foreign bodies and splashing water).
Acceptance method: Visually check the gaps in the cabinet and plug the inlet holes (fireproof mud or sealant is required), and check the marking of protection grade in the design drawings.
3. Component installation and wiring
Mechanical strength: circuit breakers, contactors and other components are installed firmly without shaking; The bolt torque of terminal block meets the requirements (for example, M4 bolt torque is 2.5 ~ 4 nm).
Wiring process:
Conductor color separation conforms to the specifications (such as phase line L1 yellow, L2 green and L3 red, zero line N light blue, PE yellow green and double color).
Multi-strand wire needs to be crimped with copper nose, bolt locking gasket is complete, and there is no exposed wire head (exploitation length is matched with terminal).
Acceptance method: randomly check the crimping quality of 5~10 terminals, lightly screw the bolts with a screwdriver to check the locking effect, and check the consistency between the cable color and the drawings.
Second, the function and performance acceptance
1. Control logic verification
Basic functions:
The start-stop button and changeover switch operate normally, and the indicator light corresponds to the state of the component (for example, the contactor should be closed when the "Run" light is on).
Interlocking function is effective (such as positive and negative circuit interlocking, fire linkage to cut off non-fire power supply).
Acceptance method: simulate the operation item by item (such as start → run → stop → fault alarm), and record whether the response of each link conforms to the design logic.
2. Protection device action test
Overload protection: the overload setting value of thermal relay and circuit breaker is 1.1~1.2 times the rated current, and the action time conforms to the load characteristics (for example, the motor load needs to be delayed for 10~20 seconds to trip).
Short-circuit protection: the breaking time of the circuit breaker is ≤0.1 second, and the fuse melt specification matches the circuit.
Acceptance method: simulate overload/short circuit condition through voltage regulator or load box, record protection action time with stopwatch, and check whether it is within the design range.
3. Operating parameters of power supply and load
Voltage/current balance:
Three-phase voltage deviation ≤5% (for example, voltage of each phase in 380V system is 361~399V), and current deviation ≤10% (when fully loaded).
Acceptance method: use multimeter or power quality analyzer to measure and record the difference of three-phase data.
Temperature rise test:
Component surface temperature ≤60℃ (such as circuit breaker handle), and copper bar joint ≤85℃ (detected by infrared thermometer).
Acceptance method: after full-load operation for 1 hour, spot check the hot spots (such as terminal strip and contactor contacts).
Iii. Acceptance of data and documents
1. Debugging report
Need to include: insulation resistance, grounding resistance test records; Measured values of voltage/current of each loop; Setting value and action time of protection device; Exception handling record.
Key points of acceptance: complete data and signatures, and the test time coincides with the commissioning date.
2. Completion drawings
It is necessary to reflect the actual wiring changes (such as loop adjustment and component replacement), and mark the cable model, terminal number and laying path.
Key points of acceptance: compare the design drawing with the field wiring, and check whether 5~10 key circuits (such as main power supply and control circuit) are consistent.
3. Product qualification certificate
Components (circuit breakers, contactors, etc.) need CCC certification, and cabinets need factory inspection reports and material certificates (such as steel plate thickness ≥1.5mm).
Key points of acceptance: check that the component model is consistent with the drawing, and check whether CCC mark and certificate date are within the validity period.
Fourth, the special requirements of the industry (some scenarios)
1. Fire power distribution system
The switching time of dual power supply is ≤0.5 seconds, and the automatic switching function of standby power supply is reliable; The fire linkage signal is fed back to the control room.
Acceptance method: simulate the power failure of the main power supply, measure the switching time with a stopwatch, and check whether the signal received by the fire control room is normal.
2. Explosion-proof distribution box (inflammable and explosive place)
The cabinet seal is not aged, the explosion-proof glen head at the inlet is screwed in place, and the grounding bolt needs to be galvanized; Explosion-proof grade (such as Ex d IIB T4) meets the environmental requirements.
Key points of acceptance: check the explosion-proof certificate, visually check the sealing surface and grounding technology, and check that the explosion-proof mark matches the site grade.
3. Intelligent power distribution system
The communication function is normal (such as Modbus protocol data uploaded to the monitoring platform), and the error between the instrument display value and the actual parameters is ≤1%.
Acceptance method: read the data through the upper computer software, and compare whether the field instrument display value is consistent with the platform data.
V. Handling Process of Unqualified Acceptance Items
Rectification within a time limit: for problems such as substandard insulation resistance and loose grounding, the construction party is required to rework and retest within 24 hours until it is qualified.
Functional re-inspection: If the protection device is overtime and the control logic is wrong, it is necessary to adjust the setting value or modify the program, re-simulate the test and record it.
Data correction: the missing test report and changed drawings shall be supplemented completely within 3 days after acceptance, and signed by the supervisor/Party A for confirmation.
Six, acceptance criteria
All items passed: electrical safety, function test and data documents all meet the specifications and design requirements, and there are no major hidden dangers (such as grounding failure and lack of protection function).
Permissible items: general items (such as the aesthetics of cable binding) have defects that do not affect safety, which need to be noted in the acceptance record, and can be judged as qualified after rectification within a time limit.
Through standardized acceptance, it can ensure that the distribution box/cabinet meets the requirements of safety, reliability, convenient operation and maintenance, and provide a solid foundation for subsequent operation and maintenance. The acceptance process shall be recorded in writing, which shall be signed by all parties (construction, supervision and Party A) and filed.
