Abstract :
H. W. Oetinger: Reference is made to the checking of instrument transformers with equivalent secondary burdens. The usual procedure in determining this secondary burden is to calculate it from the published data of the instrument coil constants and the size and length of leads. Where test wiring is used exclusively, there can be no question regarding this procedure but where the test instruments are inserted in conjunction with station instruments and wiring, there is some question as to what is actually in the circuit. In one case it was found that coils of unknown and variable volt-ampere characteristics were left in circuit. In such cases it seems desirable to actually measure the secondary burden and include all connections and instruments to be used during the test. A voltmeter, ammeter and wattmeter can be used in conjunction with a load box. The disconnection is made at the terminals of the instrument transformers and voltage applied to the leads at this point.
