Atec Chroma-63800 Series - Manual (Page 4)

Figure 8: Fixed Bandwidth Figure 9: With ABA
Comprehensive Measurements
Figure 7:
Transfer time for Off-Line UPS
Automatic Bandwidth Adjustment (ABA)
The examples on the right compare voltage and current
waveforms using traditional fixed bandwidth (@15kHz)
load and the Chroma 63800 load for UPS load
simulation. Noticeable difference can be observed with
or without the ABA.
When the UUT has higher output impedance such as
Generator, the current waveform won't be stable as
shown below without ABA. In most cases, the loading
current will be oscillating and spoil the test.
When using active load mode (CC,CP), traditional AC loads operate under fixed bandwidth. When the load is working at low control
bandwidth will limit the load from simulating high crest factor loading. In opposite, increase control bandwidth will influence the control
loop stability especially when the UUT output impedance is high. To resolve this problem in traditional AC load, Chroma 63800 AC/DC
Load dynamically adjusts the operating bandwidth by detecting the impedance*¹ of the UUTs to alleviate the risk of system instability.
Note 1: A test current will be programmed prior the actual loading defined by user for impedance detection.
Parallel / 3-Phase Control
The 63800 series provides parallel and 3-phase functions for
high power and three phase applications. All the models within
the 63800 series can be used together for both parallel and
3-phase functions as well as paralleled AC Load units in 3-phase
configuration, providing excellent flexibility and cost savings for
the 63800 series AC load. Parallel and 3-phase controls are
made easy by linking the AC Load units together, control of all
AC load units will be made through the Master Unit. Connections
of parallel and 3-phase functions are as shown in Figures 11, 12
and 13.
Figure 10: Parallel connection
Figure 11: Parallel/3-Phase Y connection Figure 12: Parallel/3-Phase Delta connection
Chroma's 63800 Series AC/DC Electronic Loads includes built-in 16-bits precision
measurement circuits to measure the steady-state and transient responses for true RMS
voltage, true RMS current, true power(P), apparent power(S), reactive power(Q), crest factor,
power factor, THDv and peak repetitive current.
In additional to these discrete measurements, two analog outputs, one for voltage and one
for current, are provided as a convenient means of monitoring these signals via an external
oscilloscope.
Timing Measurement
Timing parameters are critical to many products such as UPS, Breaker and Fuse. The 63800 AC/DC Load also includes unique timing
measurement function to measure the trip time of fuse & circuit breaker or the transfer time for UPS (Off-Line).