In high revenue areas such as universities, shopping malls and business centres, taking CT's offline is not an option so a
a reliable live CT test alternative is required.
The 505B (pictured) can test metering CTs live at 50Hz or 60Hz and uses a 1.6kHz admittance measurement technique to detect faults which indicate metering errors such as:
errors in metering circuits shorted to ground, shorted turns and tampeA faulty metering CT can cause large revenue losses and with admittance testing only adding an extra 10 minutes to a routine polyphase meter test, this is a quick and easy method to check the integrity of the utility's instrumentation metering components.

The Model 505B is battery powered and field portable. A 2 terminal device, it is inserted into the CT secondary loop and during test it injects a small 1.6kHz signal into the secondary metering circuit.
The signal is superimposed onto the existing 50Hz or 60Hz current already flowing in this circuit and a
1.6kHz admittance measurement is filtered out and taken from this.

The 505B can measure voltage and current at 50 or 60Hz and it is also able to calculate a CT's or VT's burden. Both 50Hz and 60Hz versions are available, and both 5A and 1A CTs can be tested.
A USB interface is also provided on the front panel for downloading results data to a PC.

The 505B can perform the following measurements:

1.6kHz admittance test on a CT secondary.
1.6kHz admittance test on a CT secondary plus the complete metering loop.
50Hz (or 60Hz) CT secondary current.
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.

Since 1999, Red Phase Instruments has led the way in the manufacture of portable CT error testing equipment.
Our portable analysis method has allowed utilities around the world to test their metering CTs easier and faster than using bulky traditional methods without jeopardizing accuracy.

Following feedback from our users, our Model 590G-V2 is the latest version of this successful and well proven CT error tester.

The 590G-V2 has all the features and advantages of the previous models with additional testing features, better accuracy and smaller size and weight.

In a world where cost control is gaining importance, this CT tester not only lowers testing costs by being simple, fool-proof and fast. It also allows utilities to pursue the very important (yet at many times forgotten) task of testing installed CTs for detecting tampering, and minimizing losses due to faulty CTs.

Test capabilities:

Offline
CT Ratio and phase error measurements to an accuracy of 0.02%.
CT 1.6 kHz Admittance test.
Graphical display or plot of the CT's excitation curve.
Burden test.
Measures CT winding resistance.
Performs a CT polarity check.
PT full load simulated tests (with 590D-1 accessory)
Live
Live CT testing (with 590F accessory)

For customers who cannot be disconnected or offline when performing metering CT tests, the 590F HV (High Voltage) accessory can be added as a retrofit kit to our popular 590C, 590G and 590GV2 CT testers.

The first part of the kit is the 590F-1, which is a clipon unit mounted on the end of a hot stick. This unit has a battery powered electronic compensation circuit for the clipon which greatly improves accuracy over a wide operating range, typically 25A to 1450A.
A microprocessor is also used to control the clipon compensation, manage the internal range changing and provide communications via a fibre optic and
RS-485 interface.

The fibre optic cable runs between the 590F-1 and a small interface unit at the base of the hotstick.
From there the signal is transmitted through a 100M drum of RS485 cable to the 590C/G or G-V2
CT tester.
The combination of hot stick and cable has been tested to 100kV, line to ground.
The actual breakdown voltage of the hotstick and fibre optic cable is much greater than 100kV,
but for operator safety we suggest not using this test set above 100kV. However, with a longer
hotstick and suitable precautions the 590F-1 unit can be used at higher voltages.

The CT primary current measured by the clipon is sent via the cable to the 590C/G or G-V2 CT Tester which can be up to 100M away. Extra drums can be daisy chained up to 400M in total. The 590C/G or
G-V2 unit measures the CT secondary current, either 1A or 5A nominal, and then calculates the CT
ratio and phase error to an accuracy of 0.1%.

For testing live LV (Low Voltage) CTs, two optional electronically compensated clipons are available.
One is for the primary side, (for cables carrying up to 1,000A) and the other is a large jaw clipon for busbars up to 2,500A.

This is an accessory to the model 590G-V2 and is used to perform full load testing of inductive PTs. It has a high power switch mode ( typically 1.2kW ) source for full load performance testing of PTs under simulated load conditions to 0.1% accuracy. It uses the existing measuring and processing functions of the 590G-V2 in combination with its own processor controlled monitoring and interface systems.
Communication between the two units is via a serial link.

The 590D-1 unit is the interface between the 590 model series and the inductive PT under test.

The 590D-1 measures:-

Primary & Secondary winding resistance.
Secondary winding admittance with primary short circuited.
Primary winding admittance calculated from turns ratio.
Turns ratio and no load voltage ratio.
Secondary admittance with primary open circuit.

Finally the microprocessor calculates the PT errors at 6 test points from the measurements taken.
These test points are typically taken at 25% and 100% of the burden rating over 80%, 100% and 120%
of rated voltage.
The 590D-1 comes with these default or standard test points already preset / programmed but the
operator is also able too add their own set of custom test points to suit via the 590C/G or G-V2 model.

This small battery powered tester is ideal for carrying out
quick burden checks in CT metering and protection circuits.

The clipon CT (pictured) is connected to the CT secondary wiring and the crocodile clips attached to the CT terminals. The instrument calculates the burden as the ratio of voltage over current.

The burden measurement accuracy is typically 1% at 5A and 5V, and decreases to 5% at 0.01A and 0.01V.

The Model 594 is a low cost, comparative tester for the rapid testing of batches of new CTs against a known sample. The test set gives a digital indication of the turns error, polarity, current error (inherent losses) and phase error (inherent losses). The unit can be preset to 12 different types of CT’s by a trimpot adjustment so that the readout is the same as the sample CT. The test method applies only at very low voltages and currents on the CT secondary winding.
Total test cycle time is about 30 seconds.

When using the conventional primary injection method to test CTs, a reference CT and a burden box must be used.
The errors are measured by a comparator or test bridge such as the Red Phase Instruments Model 820.
The 820 has digital readouts for ratio and current error, plus it measures the current in the CT secondary, the burden voltage across the terminals and the burden power factor.

The overall accuracy of error measurement depends on the
errors in the reference CT plus the measurement error of the
comparator. The 820 comes in a 19" rack mounted form factor
and is usually built into a laboratory or workshop test bench.

For checking mini CTs as used in electronic kWh meters we also make the Model 820A in the same 19" form factor. This model has an internal reference CT with multiple taps, rated up to 100A primary current. It can test any mini CT with ratios from 100:1 up to 3000:1.

When the requirement calls for a comparator to be used in field testing we have the Model 820B which is essentially the same as the 820, but this time housed in a portable carry case.

Our 590 reference CT is a valuable multi-tap reference platform for the calibration and accuracy certification of our 590 series of CT Testers.
Multiple primary turns are fitted to increase accuracy for testing low ratio CTs. The error of a reference CT is very dependent on the ratio selected for testing. These are not electronically compensated, and have errors that are better than 0.01% for higher ratios. The reference CT comes in a rugged pelican case with a selectable tap switch and terminal posts for connection..