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Isolator Switch Use Relay Protection Action Trip
Jul 12, 2017

Isolation switch does not have a special arc extinguishing device, can not be used to connect and break the load current and short circuit current, otherwise it will produce a strong arc, causing personal injury, equipment damage or cause interphase short circuit failure. So the isolation switch points, together with the general operation and circuit breaker with. The effect of the disconnector is:

(1) Isolation of power In the maintenance of electrical equipment, in order to be safe, need to use the disconnector to the power outage maintenance equipment and charged running equipment isolation, the formation of a clear fracture. Isolated power supplies are the primary use of disconnectors.

(2) switching operation In the double busbar down the bus or turn on the bypass bus, some disconnectors can be in the "equipotential" in the case of sub-closing, with the circuit breaker to complete the switching operation.

(3) points, and small current can be used to sub-combined, voltage transformer, arrester and no-load bus; sub-excitation current is less than 2A no-load transformer; closed capacitor current less than 5A no-load lines.

Disconnector, which is known as a knife, is one of the most important and common high-voltage electrical installations, and its selection and technical requirements are detailed in Chapter 11 of the DL / T5222-2005 and in Section 6-3 of the manual Introduction, usually represented by GW (outdoor) and GN (indoor) symbols.

First, the single column vertical open disconnector in the sub-gate state, the minimum distance between the static and dynamic contacts should not be less than the minimum safety clearance of the power distribution device B1 value.

Second, the isolation switch should still be able to reliably cut off the circuit breaker bypass current and bus current circulation. The text of this specification does not give a specific value of the excision of the busbar circulation, need to look at the description to find. On the general isolation switch breaking current 0.8In (In for the product rated current), opening and closing times 100 times, opening and closing voltage: 10kV grade products 50V; (35 ~ 110) kV grade products 100V; 220kV level above products 300V, 400V. If you do not read carefully, this simple and easy to know the point of knowledge is really easy to be ignored.

Third, the disconnector configuration in what place, there are grounding disconnector configuration where is easy to find in the wrong title, although I do not recommend that you choose to find the wrong title, but the review should still be in place. In the circuit breaker on both sides of the need to configure the disconnector, which is clearly clear things, but the world, everything is not absolute. In the following case, the isolation switch is only provided on the side of the circuit breaker, but this is also true because the transformer is exited with the circuit breaker when the circuit breaker is overhauled, so that one of the circuit breakers and the transformer can be saved Disconnector.

Fourth, in the gas-insulated metal-enclosed switchgear power outage of the first grounding point (can be pre-determined that the loop is not charged) or the use of grounding device to protect the enclosure should be selected when the fast grounding switch, and in other cases, the choice of general grounding Turn off. May not have been exposed to GIS equipment, students will be very puzzled that the fast grounding switch is something that is straightforward, it is very fast grounding switch, usually with FES (fast) that is the use of fast grounding switch action is very Fast this feature, can not determine whether the loop is charged, we use a quick grounding switch to ground to prevent the case in case of live, the use of ordinary grounding switch, resulting in arc discharge phenomenon, the arc generated a huge heat to burn GIS Of the outer tube, resulting in irreparable permanent damage, or cause GIS scrapped. In another case, in the event of a non-metallic single-phase earth fault, due to the safety of the generated arc threat to the GIS device housing, we use a fast grounding switch to create a man-made ground, resulting in metal ground fault, and then use the relay Action trip, remove the fault circuit, so as to further expand the accident.