- Modular based design — user configurable TM1800 from nine different modules
- Built in PC with CABA Local software — advanced testing with predefined breaker test plans (templates), onsite measurement view and analysis
- Dual ground testing using DCM module — increased safety with both sides of breaker grounded
- Fast and easy testing — Select-Connect-Inspect workflow and high level user interface
- Graphical results for quick interpretation — timing and motion measurements, coil currents
- USB and Ethernet communication interface — for quick back up, LAN connection and printer options
- CABA Win — for advanced data analysis, database interface and common test data archive
The TM1800 is the instrument platform for circuit breaker maintenance, based on more than 20 years’ experience of over 4,000 delivered breaker analyzers. The modular construction makes it possible to configure the TM1800
for measurements on all known types of circuit breakers in operation in today’s power world.
Simultaneous measurements within a single phase are important in situations where a number of contacts are connected in series. Here, the breaker becomes a voltage divider when it opens a circuit. If the time differences are too great, the voltage becomes too high across one contact, and the tolerance for most types of breakers is less than 2 ms.
The time tolerance for simultaneous measurements between phases is greater for a 3-phase power transmission system running at 50 Hz since there is always 3.33 ms between zero-crossovers. Still, the time tolerance is usually specified as less than 2 ms, even for such systems. It should also be noted that breakers that perform synchronized breaking must meet more stringent requirements in both of the previously stated situations.
There are no generalized time limits for the time relationships between main and auxiliary contacts, but it is still important to understand and check their operation. The purpose of an auxiliary contact is to close and open a circuit. Such a circuit might enable a closing coil when a breaker is about to perform a closing operation and then open the circuit immediately after the operation starts, thereby preventing coil burnout.
The "a" contact must close well in advance of the closing of the main contact. The "b" contact must open when the operating mechanism has released its stored energy in order to close the breaker. The breaker manufacturer will be able to provide detailed information about this cycle.
A high-voltage breaker is designed to interrupt a specific short circuit current, and this requires operation at a given speed in order to build up an adequate cooling stream of air, oil or gas (depending on the type of breaker). This stream cools the electric arc sufficiently to interrupt the current at the next zero-crossover. It is important to interrupt the current in such a way that the arc will not re-strike before the breaker contact has entered the so-called damping zone.
Speed is calculated between two points on the motion curve. The upper point is defined as a distance in length, degrees or percentage of movement from a) the breaker’s closed position, or b) the contact-closure or contact-separation point. The time that elapses between these two points ranges from 10 to 20 ms, which corresponds to 1-2 zero-crossovers.
The distance throughout which the breaker’s electric arc must be extinguished is usually called the arcing zone. From the motion curve, a velocity or acceleration curve can be calculated in order to reveal even marginal changes that may have taken place in the breaker mechanics.
Damping is an important parameter for the high energy operating mechanisms used to open and close a circuit breaker. If the damping device does not function satisfactorily, the powerful mechanical strains that develop can shorten breaker service life and/or cause serious damage. The damping of opening operations is usually measured as a second speed, but it can also be based on the time that elapses between two points just above the breaker’s open position.
These can be measured on a routine basis to detect potential mechanical and/or electrical problems in actuating coils well in advance of their emergence as actual faults. The coil’s maximum current (if current is permitted to reach its highest value) is a direct function of the coil’s resistance and actuating voltage. This test indicates whether or not a winding has been short-circuited.
When you apply a voltage across a coil, the current curve first shows a straight transition whose rate of rise depends on the coil’s electrical characteristic and the supply voltage (points 1-2). When the coil armature (which actuates the latch on the operating mechanism’s energy package) starts to move, the electrical relationship changes and the coil current drops (points 3-5). When the armature hits its mechanical end position, the coil current rises to the current proportional to the coil voltage (points 5-7). The auxiliary contact then opens the circuit and the coil current drops to zero with a current decay caused by the inductance in the circuit (points 7-8).
The peak value, of the first lower current peak, is related to the fully saturated coil current (max current), and this relationship gives an indication of the spread to the lowest tripping voltage. If the coil was to reach its maximum current before the armature and latch start to move, the breaker would not be tripped. It is important to note, however, that the relationship between the two current peaks varies, particularly with temperature. This also applies to the lowest tripping voltage.
Dynamic resistance measurement (DRM)
A circuit breaker will have arcing contact wear by normal operation as well as when breaking short-circuit currents. If the arcing contact is too short or otherwise in bad condition, then the breaker soon becomes unreliable. Main contact surfaces can be deteriorated by arching, resulting in increased resistance, excessive heating and in worst-case explosion.
The main contact resistance is measured dynamically over an open or close operation in DRM. With DRM measurement the arcing contact length can be reliably estimated. The only real alternative in finding the length of the arcing contact is dismantling the circuit breaker.
A reliable DRM interpretation requires high test current and a circuit breaker analyzer with good measurement resolution.
Vibration analysis is a noninvasive method using an acceleration sensor without moving parts. The breaker can stay in service during the test. An Open-Close operation is all that is required for the measurement. The first operation can be different compared to the second and third because of corrosion and other metal to metal contact issues. Vibration is an excellent method to capture the first operation after long time in the same position.
The analysis compares the vibration time series with earlier taken reference. The vibration method detects faults that can hardly be indicated with conventional methods. But if conventional data such as contact time, travel curve, coil current and voltage are available in addition to the vibration data even more precise condition assessment is possible. The vibration data is stored together with available conventional data.
The Vibration method is published in CIGRÉ and IEEE® papers. Since about 20 years is it utilized in the industry for testing all kind of breakers from transmission and distribution to industrial sites. The method was first established on the Scandinavian market. Vibration can be performed under very safe manners for the test technician as both sides can be grounded throughout the test. Also less climbing is required since no access to the breaker contact system is needed, the acceleration sensor is easily mounted on the breaker.
Select – Connect – Inspect
Working with TM1800 means fast and easy testing. Testing is done with a three-step process.
First step is to select a suitable template from the template library depending on number of contacts per phase, motion or not, resistor contacts and more.
Second step is to connect the test leads according to the graphical help screen.
Third step is to turn the “Measure” knob. The measurement is performed, analyzed and the results will be displayed on the screen. Magnification and compare functions are available.
For more advanced setup there is still the opportunity to control all the details in the measurement. The large number of general purpose templates cover most circuit breakers found around the world. It is also possible to select a tailor made template with special our customer support. This is a very powerful tool to customise TM1800 for fast and easy work according to your needs in every detail. Increase the level of detail as you learn.
After the test it is possible to print a test report, either from the TM1800 printer module or using CABA Win on a PC. With CABA Win you can make a more advanced analysis of the data. CABA Win is also the archive for common test data and interface to CBEX. With CBEX the test is stored in a database.
6 Timing and 3 Motion
Circuit breaker: Any CB with two contacts per phase and separate drives
TM1800 configuration: TM1800 Expert
1 Select breaker template: Generic templates / 2 breaks per phase / Separate drives / Two Control modules / No resistor contact / Motion
2 Connect cables according to "Analyzer view" in CABA Local. Turn the OPERATE/MEASURE knob.
3 Inspect the result on screen.
Coil current and auxiliary contacts are measured and displayed automatically.
If TM1800 is configured with a DCM module the test can be made using DualGround.