A diagnostic apparatus comprising: a first input interface configured to receive a first monitor current that is proportional to a primary winding current of a transformer; a second input interface configured to receive a second monitor current that is proportional to a secondary winding current of the transformer; and characterized by a third input interface configured to receive DGA data from a dissolved gas analysis apparatus; at least one processor configured to: - execute an electrical current flow analysis of the transformer based at least in part on the first monitor current and the second monitor current; - detect, based on the electrical current flow analysis, a through-fault condition; - detect from the received DGA data, an abnormal gas-related condition; and - generate transformer health data based at least in part on the through-fault condition and the abnormal gas-related condition; and an output interface configured to transmit from the diagnostic apparatus, at least one of a transformer health related signal or a control signal based on the transformer health data; wherein the current flow analysis comprises: calculating a differential electrical current value and a restraining electrical current value based on the primary winding current and the secondary winding current of the transformer; deriving real-time electrical current flow data of the transformer by comparing a ratio of the differential electrical current value and the restraining electrical current value to a threshold value; identifying a first instant in time at which the ratio exceeds the threshold value; fetching from a storage element, historical electrical current flow data of the transformer; generating cumulative electrical current flow data of the transformer by combining the historical electrical current flow data and real-time electrical current flow data obtained at the first instant in time and subsequent to the first instant in time; and detecting the through-fault condition based on the cumulative electrical current flow data of the transformer. a first input interface configured to receive a first monitor current that is proportional to a primary winding current of a transformer; a second input interface configured to receive a second monitor current that is proportional to a secondary winding current of the transformer; and characterized by a third input interface configured to receive DGA data from a dissolved gas analysis apparatus; at least one processor configured to: - execute an electrical current flow analysis of the transformer based at least in part on the first monitor current and the second monitor current; - detect, based on the electrical current flow analysis, a through-fault condition; - detect from the received DGA data, an abnormal gas-related condition; and - generate transformer health data based at least in part on the through-fault condition and the abnormal gas-related condition; and - execute an electrical current flow analysis of the transformer based at least in part on the first monitor current and the second monitor current; - detect, based on the electrical current flow analysis, a through-fault condition; - detect from the received DGA data, an abnormal gas-related condition; and - generate transformer health data based at least in part on the through-fault condition and the abnormal gas-related condition; and an output interface configured to transmit from the diagnostic apparatus, at least one of a transformer health related signal or a control signal based on the transformer health data; wherein the current flow analysis comprises: calculating a differential electrical current value and a restraining electrical current value based on the primary winding current and the secondary winding current of the transformer; deriving real-time electrical current flow data of the transformer by comparing a ratio of the differential electrical current value and the restraining electrical current value to a threshold value; identifying a first instant in time at which the ratio exceeds the threshold value; fetching from a storage element, historical electrical current flow data of the transformer; generating cumulative electrical current flow data of the transformer by combining the historical electrical current flow data and real-time electrical current flow data obtained at the first instant in time and subsequent to the first instant in time; and detecting the through-fault condition based on the cumulative electrical current flow data of the transformer. calculating a differential electrical current value and a restraining electrical current value based on the primary winding current and the secondary winding current of the transformer; deriving real-time electrical current flow data of the transformer by comparing a ratio of the differential electrical current value and the restraining electrical current value to a threshold value; identifying a first instant in time at which the ratio exceeds the threshold value; fetching from a storage element, historical electrical current flow data of the transformer; generating cumulative electrical current flow data of the transformer by combining the historical electrical current flow data and real-time electrical current flow data obtained at the first instant in time and subsequent to the first instant in time; and detecting the through-fault condition based on the cumulative electrical current flow data of the transformer.