Two independent models simulate dynamic and steady-state responses of electrical and electronic equipment under power load. One is resistance/capacitance/inductance network, and the other is variable resistance analog device. Resistance, inductance, and/or capacitance are selected by iterative process; time-domain response is compared with that of real equipment to select optimal values

Birnbach, S.

Joncas, K. P.

Lambert, M., III

English

NASA Technical Reports Server

August 1973	 UPDATED COPY	 B73-10305 
Updated August 1974
NASA TECH BRIEF 
Lyndon B. Johnson Space Center 
! 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Dynamic Power Load Simulator 
.
The problem: 
The optimal design of electrical power distribution 
and conditioning systems depends upon the character-
istics of the power sources and the loads. In many cases, 
it is important to evaluate system performance under 
true load conditions. However, present electrical power 
load simulators can reproduce only steady-state con-
ditions. The full-scale dynamic, or transient, electrical-
load power profile cannot be accurately simulated. For 
this reason, low voltages, effects on other loads, and 
other potential problems arising from inadequate dy-
namic load design cannot be evaluated. 
The solution: 
Two different and independent models have been 
developed to simulate the dynamic and steady-state 
responses of electrical and electronic equipment under a 
power load. One is a resistance/capacitance/inductance 
network, and the other is a variable resistance analog 
device. Resistance, inductance, and/or capacitance are 
selected by an iterative process; the time-domain re-
sponse is compared, by a computer program, with that 
of the real equipment to select optimal values.
How it's done: 
Both devices are part of an overall test system shown 
in the block diagram. Equipment successfully tested 
includes switches, inverters, transceivers, and beacons. 
The test procedure is divided into two phases: an 
equipment interrogation phase and a simulation phase. 
The interrogation phase comprises the quantitative 
determination of parameters that describe the dynamic 
and steady-state electrical response of the power lines to 
specified voltages. The simulation phase is the dupli-
cation, on the power lines, of the dynamic and steady-
state response of an electrical load. 
The interrogation phase begins with data acquisition, 
which is the same for both simulators. The operating 
voltage is applied to the equipment, and voltage and 
current versus time are recorded. The power source, 
shunts, wiring, and the necessary interface equipment are 
included in this process. 
The voltage and current characteristics are then 
analog recorded on tape. An editing capability allows 
the quality of the recorded data to be quickly reviewed. 
For the network simulator, the data is converted to 
digital form and computerized. From an initial estimate, 
Equipment H Data	 Data Review Acquisition	 and Under Test Editing 
Starting	 St toning 
Topology
	
Element 
Values Model 
Set-Up 
Analog to Data 
Digital	 Optimization 
Conversion
SequenceModel 
Data
Simulator 
--
Interface 
Voltage	 r
Control	 VariableR 
Current
Signal 
Computation L_ Dynamic Load Simulator 
Interrogation	 - '	 Simulation -'ç----s.. 
Interrogation/Simulation System
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights. 
0.
https://ntrs.nasa.gov/search.jsp?R=19730000305 2020-03-17T06:59:27+00:00Z
the computer iteratively selects the optimal resistor, 
inductor, capacitor, and time-delay values to match the 
real equipment. The appropriate values are manually 
set in the simulator. 
The - model network simulator is a three-branch 
electrical network of discretely variable resistors, capac-
itors, and inductors. For the simulation of discontinuous 
or complex waveforms, the branches may be introduced 
or removed at specified times during the test. 
The variable resistance simulation requires that the 
analog data be processed somewhat differently. A 
resistance network divides the voltage data by the 
current data to give a resistance equivalent. This in-
formation goes to a tape storage and is played back as 
the input voltage control for the variable resistance 
simulator. Several dynamic simulations may be run in 
parallel or in series. The output resistance of the 
simulator is connected to the power source which 
operates the real equipment. Thus the power input 
current is made to vary just as the input current to the 
real equipment. 
Both models are capable of simulating loads with 
the following power characteristics, but the variable-
resistance simulator is limited to positive, non-zero-
crossing voltages: 
Voltage: (a) 100 to 130 V, 60 to 400 Hz, single phase 
(b) 20 VDC to ground 
Current: Up to 8 A 
Power: Upto25OW
Note: 
The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $14.00 
(or microfiche $0.95) 
Reference: NASA CR-i 15760 (N72-30248) 
Dynamic Load Simulator, Final Report. 
Patent status: 
NASA has decided not to apply for a patent. 
Source: K. D. Castle of 
Johnson Space Center and
M. Weinberger, C. Russell, Jr., K. P. Joncas,
S. Birnbach, and M. Lambert III of 
Avco Corp.
under contract to
Johnson Space Center
(MSC-14285, 14286)
is 
B73-10305
	 Category 02


Dynamic power load simulator

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