Utitlity Test Solutions

Live CT Tester: MODEL 505B

In high revenue areas such as universities, shopping malls and business centres, taking CT's offline for testing is not an option, so a reliable live CT test alternative is required.

Live CT testing using admittance...

A component of a good CT's characteristic performance is a low admittance value. This admittance value can be measured while in-circuit using the 505B (pictured).

The 505B is placed in series with an in-circuit CT and it superimposes a small 1.6kHz signal onto the live 50 or 60Hz secondary metering circuit.

A filter on board the 505B extracts the 1.6kHz admittance reading and from this a quick determination is made on the CT's general health.

Admittance testing only adds an extra 10 minutes to a polyphase meter test and is quickly becoming part of a routine test requirement for some utilities.

The 505B can perform the following measurements:

• Voltage and current at 50 or 60Hz.
• 1.6kHz admittance test on a CT secondary.
• 1.6kHz admittance test on a CT secondary plus the complete metering loop.
• VA burden of the metering loop downstream from the test block, or at the CT secondary terminals.
• VA burden of the metering loop from VT secondary terminals or at its test block.

A USB interface is also provided on the front panel for downloading results data to a PC.