Fuse handcarts,voltage transformer handcarts, isolation handcarts, grounding handcarts, and Electric handcart in high-voltage switchgear (such as KYN, center cabinet, etc.). They have significant differences in structure, function and application scenarios. The following is a detailed comparison of them:
1. Fuse handcarts
Function:
Integrated high-voltage fuses (such as current-limiting fuses) are used to protect circuits from overload or short-circuit current damage, usually used in conjunction with load switches or contactors.
Features:
Fuse is a one-time component and needs to be replaced after a fault.
Commonly used for the protection of equipment such as transformers and capacitors.
Typical applications:
Such as the fuse module in the "load switch-fuse combination appliance".
2. Voltage Transformer handCart (PT Cart)
Function:
Install a voltage transformer (PT) to convert high voltage into low voltage (such as 100V) in proportion for use in measurement, metering or protection devices.
Features:
The design of the cart facilitates the maintenance or replacement of the PT.
The secondary side of the PT needs to be reliably grounded to prevent high voltage from entering the low-voltage circuit.
Typical applications:
Used for bus voltage monitoring, energy metering or relay protection circuits.
3. Isolation handcarts
Function:
Realize physical isolation of the circuit (without arc extinguishing capability), ensure that the circuit has an obvious disconnection point during maintenance, and ensure safety.
Features:
Operation without load: must be operated after the circuit breaker is opened.
Simple structure, usually without arc extinguishing device.
Typical application:
Used for busbar isolation, incoming or outgoing line isolation, forming a visible electrical breakpoint.
4. Grounding handcarts(Grounding Switch Cart)
Function:
Actively ground the high-voltage circuit to release residual charge to prevent mis-powering or induced electric shock during maintenance.
Features:
Divided into maintenance grounding (manual operation) and fault closing grounding (fast grounding switch).
Must be used in conjunction with an isolating cart or circuit breaker.
Typical application:
Safely ground the busbar or cable before maintenance.
5. Electricity tester trolley (electricity tester trolley)
Function:
Check whether the high-voltage circuit is energized and confirm that the equipment is in a de-energized state.
Features:
Integrated electrician (such as a live display device or a direct contact electrician test pen).
Usually needs to be used in conjunction with a grounding trolley.
Typical applications:
Verify whether the circuit is voltage-free before maintenance to ensure safe operation.
Precautions
Operation sequence: The operation of the isolation trolley and the grounding trolley must strictly comply with the "five-protection" logic (such as first opening the circuit breaker → then pulling the isolation trolley → finally closing the grounding trolley).
Safety specifications: The electric test trolley and the grounding trolley are the key to maintenance safety, and their functional reliability needs to be checked regularly.
The selection of different trolleys depends on the wiring scheme and protection requirements of the switch cabinet. In actual applications, they may be used in combination (such as "PT+fuse" trolley).
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