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Checking the dynamic and thermal stability of the busway

  • Categories:Zhongrui News
  • Author:
  • Origin:
  • Time of issue:2019-05-29 17:45
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(Summary description)When the busbar slot is short-circuited, there is a short-circuit current that is many times larger than the normal operating current flowing from the power supply through the high-current bus to the short-circuit point. This short-circuit current is often above 15KA, which has a force (mechanical) and thermal effect on the busbar. For this purpose, the ability of the busbar to withstand the effects of short-circuit currents must be verified, ie the dynamic stability and thermal stability of the busbars are verified. The current-carrying busbar is converted into heat due to resistance-induced losses, causing the busbar temperature to rise. Although the copper and aluminum materials themselves can be used at higher temperatures without affecting the mechanical strength, the contact surface temperature of the bolted joint is high and easily oxidized, so that the contact surface resistance is increased. The increase in contact resistance causes the contact surface temperature to continue to rise, causing a vicious cycle, resulting in damage to the contact portion. Therefore, the oxidation problem of the electrical contact surface becomes a major factor limiting the temperature of the busbar. Silver-plated bolted joints allow for higher busbar temperatures but are costly and are typically bolted or galvanized. The allowable temperature of this busbar is lower. In China, the allowable temperature of the busbar is 85-90 °C. For the closed busbar, the allowable temperature of the outer casing is 65-70 °C. When welding is used, the temperature is allowed to reach 110 °C. The thermal effect of the short-circuit current in the event of an accident should also be considered in the general bus design. In the case of a short circuit in the power grid, although the protection relay can react quickly and cut off the circuit, the delay time is only within a few seconds to ten seconds, but due to the large short-circuit current, the heat generated is also extremely large, causing the busbar temperature to be short. The time has risen dramatically. The ability of the busbar to safely withstand this short-circuit thermal effect is known as short-circuit thermal stability.

Checking the dynamic and thermal stability of the busway

(Summary description)When the busbar slot is short-circuited, there is a short-circuit current that is many times larger than the normal operating current flowing from the power supply through the high-current bus to the short-circuit point. This short-circuit current is often above 15KA, which has a force (mechanical) and thermal effect on the busbar. For this purpose, the ability of the busbar to withstand the effects of short-circuit currents must be verified, ie the dynamic stability and thermal stability of the busbars are verified. The current-carrying busbar is converted into heat due to resistance-induced losses, causing the busbar temperature to rise. Although the copper and aluminum materials themselves can be used at higher temperatures without affecting the mechanical strength, the contact surface temperature of the bolted joint is high and easily oxidized, so that the contact surface resistance is increased. The increase in contact resistance causes the contact surface temperature to continue to rise, causing a vicious cycle, resulting in damage to the contact portion. Therefore, the oxidation problem of the electrical contact surface becomes a major factor limiting the temperature of the busbar. Silver-plated bolted joints allow for higher busbar temperatures but are costly and are typically bolted or galvanized. The allowable temperature of this busbar is lower. In China, the allowable temperature of the busbar is 85-90 °C. For the closed busbar, the allowable temperature of the outer casing is 65-70 °C. When welding is used, the temperature is allowed to reach 110 °C. The thermal effect of the short-circuit current in the event of an accident should also be considered in the general bus design. In the case of a short circuit in the power grid, although the protection relay can react quickly and cut off the circuit, the delay time is only within a few seconds to ten seconds, but due to the large short-circuit current, the heat generated is also extremely large, causing the busbar temperature to be short. The time has risen dramatically. The ability of the busbar to safely withstand this short-circuit thermal effect is known as short-circuit thermal stability.

  • Categories:Zhongrui News
  • Author:
  • Origin:
  • Time of issue:2019-05-29 17:45
  • Views:
Information

When the busbar slot is short-circuited, there is a short-circuit current that is many times larger than the normal operating current flowing from the power supply through the high-current bus to the short-circuit point. This short-circuit current is often above 15KA, which has a force (mechanical) and thermal effect on the busbar. For this purpose, the ability of the busbar to withstand the effects of short-circuit currents must be verified, ie the dynamic stability and thermal stability of the busbars are verified. The current-carrying busbar is converted into heat due to resistance-induced losses, causing the busbar temperature to rise. Although the copper and aluminum materials themselves can be used at higher temperatures without affecting the mechanical strength, the contact surface temperature of the bolted joint is high and easily oxidized, so that the contact surface resistance is increased. The increase in contact resistance causes the contact surface temperature to continue to rise, causing a vicious cycle, resulting in damage to the contact portion. Therefore, the oxidation problem of the electrical contact surface becomes a major factor limiting the temperature of the busbar. Silver-plated bolted joints allow for higher busbar temperatures but are costly and are typically bolted or galvanized. The allowable temperature of this busbar is lower. In China, the allowable temperature of the busbar is 85-90 °C. For the closed busbar, the allowable temperature of the outer casing is 65-70 °C. When welding is used, the temperature is allowed to reach 110 °C. The thermal effect of the short-circuit current in the event of an accident should also be considered in the general bus design. In the case of a short circuit in the power grid, although the protection relay can react quickly and cut off the circuit, the delay time is only within a few seconds to ten seconds, but due to the large short-circuit current, the heat generated is also extremely large, causing the busbar temperature to be short. The time has risen dramatically. The ability of the busbar to safely withstand this short-circuit thermal effect is known as short-circuit thermal stability.

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