Toshiba GR-200-5 Instruction Manual

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6F2T0207 (0.01)GRE200 (5,6)- 333 -characteristic determined by the motor start-up current (Ist) and the allowable lockedrotor time (Tsc).If the motor current is larger than 2.5 times the motor rated current, the thermal state ofthe rotor can be calculated in Equation (2.28-10). Furthermore, if the thermal state of rotor(θr) exceeds the allowable thermal capacity of rotor (θrm), the Mot-LKRT element operates.θr = θr(0) + (𝐼(𝑡)𝐼𝑠𝑡)2∙ 1𝑇𝑠𝑐∙ θ𝑟𝑚 ∙ t (2.28-10)whereθr thermal state of rotor (percentage), showing allowable thermal capacityθr(0) thermal state of stator (percentage) when the rotor is lockedI(t) motor currentIst motor start-up current, defined by the setting [Mot-LKRT-IS]Tsc allowable locking time in the cold state, defined by the setting [T-Mot-LKRT]θrm allowable thermal capacity of rotor as a percentage of θs (thermal state ofstator), defined by setting [Mot-LKRT](ii) Operating timeIf the rotor is being locked, an operating time can be varied depending on the heatedcondition of the motor and the conducting current.The below equations are provided to calculate the operating time for every condition, if motorstart-up current enters when the rotor is being locked.Motor in cool conditionIn the cool condition, θr(0) = 0 and I(t) = Ist are substituted in Equation (2.28-10).As a results, the operating time t is Tsc (t = Tsc).Motor in hot condition (Motor has been running at motor rated current for along period)In the hot condition, θr(0) = θsn and I(t) = Ist are substituted in Equation (2.28-10).As a results, the operating time Tsh is given by Equation (2.28-11).𝑇𝑠ℎ = 𝜃𝑟𝑚 − 𝜃𝑠𝑛𝜃𝑟𝑚∙ 𝑇𝑠𝑐 (2.28-11)whereTsh operating time in the hot conditionθsn thermal state of the stator at motor rated current, given by