Due to their relatively special current-characteristic PANICKKER HT fuses are excellently suited for protecting HT-motors with normal and difficult starting conditions. The suitable motor fuse for certain operating conditions can be taken from illustration fig 1 to 3. The nominal current of the HT fuse to be found is taken from the ordinate and depends on the motor starting current Istart (abscissa value) and the frequency of starts (parameter value) for the various run-up periods of a motor of 6 s, 15 s and 60 s. the digits 2, 4, 6, 10, 15 and 30 along the individual characteristics stand for the number of motor starts within one hour time. In case Panickker HT fuses are used in conjunction with vacuum contactors for protecting H.T-motors, it must be born in mind that these vacuum-contactors are only designed for switching currents up to the rated current of contactor. Shot-circuit protection must therefore be taken care by the HT fuses To avoid the contact-welding of the contactors, the maximum cut-off current of the HT fuse used must always be lower than the dynamic current the contactor can take , this value to be checked with the manufacture of contactor before application. In case of doubt, please mention starting current, starting period and starting frequency per hour of the motor to be protected with fuses. Also the dynamic current of the contactor to be provided for our technical support. Cut off current curves of fuses are given below
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