DDA-3000 and DDA-6000 Universal circuit breaker test sets
Low voltage power and molded-case circuit breakers specially designed testers
Low voltage power and molded-case circuit breakers specially designed testers
Key Benefits
- Initiating control circuit
- Zero dc offset
- Construction
- Fully digital initiating control circuit provides both pulsed and maintained control modes of output duration. The pulsed mode automatically pulses the output to any programmed pulse duration. This provides additional testing capabilities for electromechanical and solid-state trip devices. A short pulse duration also limits the preheating of the breaker under test while setting the test current.
Description
Model DDA-1 digital data acquisition instrumentation and control system
High current output: 60 000 A for model DDA-6000; 35 000 A for model DDA-3000
Digital signal processing (DSP) technology
Variable pulse time and firing angle output current control
Compliant with NEMA AB-4 test guidelines
The DDA-3000 and DDA-6000 universal circuit breaker test sets are designed specifically to test low voltage power and molded-case circuit breakers equipped with thermal, magnetic, or solid-state trip devices. Universal in application, the test sets will test virtually all low voltage, molded-case, and metal-clad, direct-acting AC circuit breakers and are fully compliant with NEMA AB-4 test guidelines.
The unique transformer and circuit design results in a high capacity test set in a very compact size. Advanced digital control and instrumentation provides you with the exact testing capacity. The test sets can also be used for other high current applications, such as verifying the ratio of current transformers and performing heat runs or primary injection testing of high voltage breakers and their associated protective relays.
The DDA-3000 and DDA-6000 perform their tests by simulating an overload or fault condition. Each test set is an integrated test system that provides a variable, high current output, incorporating all control circuitry and instrumentation necessary to test direct-acting circuit breakers accurately, efficiently, and safely. All DDA-3000 and DDA-6000 test sets have identical features, instrumentation, and operational characteristics. The only changes in the specifications between the units are their size, weight, and maximum output-current capacity:
Model DDA-3000 is rated for testing breakers up to 3000 amperes
Model DDA-6000 is rated for testing breakers up to 6000 amperes
Specifications
Frequently Asked Questions
How does the DDA model number compare to other manufactures with similar model numbers?
Megger is unique in that the model number, 6000 for example, is the size of the breaker that the unit can test. The DDA6000 can push 60,000 amps through a breaker and 100,000 through a short circuit. Most manufactures use the short circuit number in their model number. For example, competitors use the model number 5000 for a unit that can push 50,000 through a short circuit. Therefore, model numbers can be confusing and when comparing be sure you compare like quantities.
What size generator is required to run a DDA3000 or DDA6000?
The output that can be achieved with either DDA greatly depends on the strength of the input voltage. If the input voltage sags then full output cannot be achieved. Therefore, the generator needs to be able to handle the very brief current demand required for testing high instantaneous values. Typically, we recommend a 150kVA or larger generator, but it depends on how good the voltage regulator responds when high current is drawn.
What size breaker is required to supply a DDA3000 or DDA6000?
Per the data sheet a 200A breaker is recommended for the DDA3000 and a 350A breaker is recommended for the DDA6000. Either will work on a smaller breaker, such as a 100 amp. However, it’s important to note that the output of the DDA(or any high current test set) is influenced by the voltage drop experienced during operation. A 100 amp breaker is typically fed by smaller wire compared to a 350 amp breaker. During high current tests, such as an instantaneous test, the DDA can draw over 800 amps of current, and the voltage drop will be more pronounced on a 100 amp service than it would be on a 350 amp service. Since this high current is typically of very short duration, the 100 amp breaker will not trip. However, the voltage sag may be more significant, slightly limiting the unit’s full output capability.
Are the DDA3000 and DDA6000 compliant with NEMA AB-4 testing guidelines?
Yes. Both DDA's can perform testing using the pulse method and adjust the firing angle to ensure output current is symmetrical.
The units are supplied with 15 ft input leads. Can long input cables be used?
The output current of the unit is considerably affected by the strength of the source. At 480 V, the DDA can draw up to 800 amps (for a very short time during instantaneous tests). Adding 40 ft of cable will result in a 1 % voltage drop, which roughly corresponds to a similar loss in output capability
