Patent ID: 9714974
Date: 2017-07-25
CPC Classifications: G01R

Claim:
1. A device for detecting an open phase in a connection line of a standby transformer in a nuclear power plant, the device comprising: a Rogowski coil installed at a neutral line of a primary Y connection line in the standby transformer used in the nuclear power plant; an open phase detector which determines that the open phase is generated when the current induced in the Rogowski coil with a preset reference value or greater maintains for a preset reference time or greater in a state that a secondary circuit breaker of the standby transformer is open to generate an alarm signal; and a main controller to display an alarm to a manager according to an alarm signal provided from the open phase detector, wherein the open phase detector comprises: a current detector which measures an intensity of the current induced in the Rogowski coil, and closes a contact point-A when the intensity of the current is equal to or greater than the reference value, and opens the contact point-A when the intensity of the current is less than the reference value; a cut-off detector which closes a contact point-B when the secondary circuit breaker of the standby transformer is open, and opens the contact point-B when the secondary circuit breaker of the standby transformer is closed; a timer which starts an operation when the contact point-A and the contact point-B are closed and closes a contact point-C when the reference time comes; and an alarm signal generator which controls to close a contact point-D corresponding to the alarm signal when the contact-C is closed, wherein the main controller displays the alarm when the contact point-D is closed.