The NPR550 series transformer differential protection device is suitable for relay protection systems in substations of 110kV and below, serving as the main and backup protection for transformers.

NPR550-TD3H digital transformer differential protection device: main protection for three coil transformers
NPR550-TD2H digital transformer differential protection device: main protection for two coil transformers
NPR550-TB1H digital transformer high backup protection device: high backup on the 110kV side of the main transformer
NPR550-TB2H digital transformer high backup protection device: high backup on the 35kV side of the main transformer
NPR550-TB3H digital transformer backup protection measurement and control device: backup on the medium and low voltage sides of the main transformer
NPR550-T3H digital non electricity protection and measurement device: non electricity protection, temperature measurement