The BROG-ZK impedance characteristic intelligent monitoring device is suitable for the protection of parallel capacitor devices in non directly grounded systems or low resistance grounded systems with voltage levels of 110kV and below, online power quality detection, and early warning protection of capacitor reactors and discharge coils. This online monitoring device can effectively detect the operating status of parallel capacitor devices. When the parameters of capacitors or reactors deviate or fail, it can provide effective warning and fault tripping protection, and can analyze and locate faults.