Available now from Megger , the BA-185 Current Transformer Burden Ammeter is a rugged, portable, multirange ammeter with switch-selected burdens.
The BA-185 Current Transformer Burden Ammeter is designed to field-test current transformer installations for a range of:
- short-circuited secondary turns
- short-circuited primary turns
- short-circuited secondary wiring
- high-resistance connections in the secondary circuit
- grounding of secondary winding when mounted on a
- grounded structure
- grounding of a normally ungrounded wire.
A good current transformer should not have a noticeable change in ratio when a secondary burden is added. This is because the primary effect of additional burden on a good current transformer is a rise in the secondary voltage.
However, if one or more turns of a current transforer are shorted, a substantial amount of the total available ampere-turns is diverted into the shunt path created by the short. Thus, the current to the circuit connected to the current transformer is less than the current transformer’s total secondary current.
Therefore, when the proper burden within the ammeter is added in series with the circuit connected to a good current transformer, the current indicated by the ammeter should only decrease a few percent.
However, in a bad current transformer, the additional burden will cause even more current to be diverted into the shorted turn or turns.
This will cause the current indicated on the ammeter to decrease significantly. This sudden and large decrease in the ammeter reading will be seen immediately whenever
the burden is added by using the switch.
Key features and benefits of BA-185 Current Transformer Burden Ammeters include:
- multirange ammeter incorporating switch-selected burdens
- burdens are normally shorted out, but can be put in series with the ammeter by a spring-loaded momentary switch
- designed to ensure that the secondary of the current transformer under test will not be accidentally opened; make-before-break construction used for ammeter range and burden selector switches
- housed in a rugged, moulded-plastic case
- all leads extend away from the user to prevent contact with live components
- optional carrying case available.