NDB-DOC-3™ Distribution Transformer Tester

The NDB-DOC-3™ is a test instrument designed for distribution networks transformers from 5kVA to 3MVA. It can determine the presence of short circuits or open circuits in the distribution transformer primary winding & also short circuits on the secondary winding.

Product Specifications

Pole top Transformer tester

The NDB-DOC-3™ is designed to be operated without disconnecting the transformer’s secondary windings from their loads.

Short circuits on secondary loads as well as internal arcing faults in gas and oil filled electrical equipment, encapsulated in metal enclosures such as distribution power transformers, can cause extensive damage and can be extremely hazardous for line crews conducting manual re-energizing. To avoid these risks utility workers are required to follow specific procedures designed to detect the presence of important fault conditions prior to any to re-energization.
Workers often find themselves under pressure to quickly remedy the power outage situations and to complicate matters even more the workers may have to deal with bad weather conditions (wind and ice storms).

transformer re-energization: - Visual inspection for obvious causes - Isolate the transformer and it’s Primary and Secondary cables - Use a Transformer Turns Ratio meter to verify that the coupling is correct. - Some utilities will perform an insulation resistance test or an Inductance type test on the primary winding and then also on the secondary winding. - Re-connect the cables - Place a new fuse - From a minimum distance of 10ft or 3 meters, re-energize the transformer.

The NDB-DOC-3 is designed to:

• Safely detect important fault conditions prior to re-energization of a transformer or a transformer bank. Whether it may be a single phase or a 3 phase transformer. WHITHOUT NEEDING TO REMOVE THE SECONDARY CABLES FROM THE TRANSFORMER OR ISOLATING TRANSFORMER IN A 3 PHASE BANK CONFIGURATION.
• Identify the short circuit conditions of the primary AND secondary from a single connection to the primary winding terminals.
• Detect Open winding condition of the primary winding
• Identify if the transformer is “ok” to be re-energized.
• Test transformer ranging 6KVA to 3000KVA
• Test medium transformers with primary voltages rating from 1KV to 50KV