Atec Megger-DDA-6000 - Manual

DDA-3000 and DDA-6000
Universal Circuit Breaker Test Sets
■
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
DDA-3000 and DDA-6000
Universal Circuit Breaker Test Sets
DESCRIPTION
Incorporating the latest technological advancements,
Models DDA-3000 and DDA-6000 Series are designed
specifically to test low-voltage power and molded-case
circuit breakers equipped with thermal, magnetic or solid-
state trip devices. The units are fully compliant with NEMA
AB-4 test guidelines.
Tests are performed by simulating an overload or fault
condition. Each test set is an integrated test system that
provides a variable, high-current output. The test sets
incorporate all control circuitry and instrumentation
necessary to test direct-acting circuit breakers accurately,
efficiently and safely.
The unique transformer and circuit design results in a very
high-capacity test set in a very compact size. Advanced digital
control and instrumentation provides exact testing capacity.
APPLICATIONS
Universal in application, the test sets will test virtually all
low-voltage, molded-case and metal-clad, direct-acting ac
circuit breakers produced by General Electric,
Westinghouse, Federal Pacific, Square D, Gould, ABB, ITE,
Siemens and other manufacturers.
Model DDA-3000 is rated for testing breakers up to 3000
amperes. Model DDA-6000 is rated for testing breakers up
to 6000 amperes. Rugged and reliable, Megger circuit
breaker test sets will provide years of trouble-free
operation.
The test sets also may 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.
All Model DDA-3000 and DDA-6000 test sets have identical
features, instrumentation and operational characteristics.
The only changes in the specifications among the units are
their size, weight and maximum output-current capacity.
FEATURES AND BENEFITS
■ Initiating control circuit: 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.
In the maintained mode, the output remains energized
until manually turned off or, during timing test, until the
device under test operates, which both stops the timer
and de-energizes the output.
■ Zero dc offset: Use of digitally controlled SCRs
instead of a contactor to initiate the output of the test set
eliminates closing-time error and thereby ensures precise
initiation at the zero crossover point of the output
current waveform every time. Initiation at the zero
crossover point ensures symmetrical output current by
eliminating dc offset in the current waveform. Therefore
accurate, repeatable test results are assured even with
currents of very short duration, as when conducting tests
of instantaneous or short-time delay trip elements.