Insulation tester checks multiple-strand electrical cables in nuclear rocket reactors. It has both manual and automatic capabilities and can check the insulation of a cable with 200 or more conductors in a few minutes

Shaw, J.

Vuckovich, M.

English

NASA Technical Reports Server

July 1967	 Brief 67-10260 
S.
ICY C
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Tester Automatically Checks Insulation of Individual Conductors in

Multiple-Strand Cables 
The problem: 
The testing of nuclear rocket reactors requires the 
use of multiple-strand electrical cables for the connec-
tion of instruments, transducers, terminal boards, etc. 
The integrity of the insulation in each cable circuit 
must be checked periodically to ensure accurate test 
results. Manual checking is a tedious and time-con-
suming operation. 
The solution: 
A cable insulation tester with both manual and 
automatic capabilities that can check the insulation of 
each conductor in a multiple-strand cable containing 
up to 200 or more conductors in a few minutes. 
How it's done: 
The cable insulation tester consists of two relay 
matrices, a combination megohm and low alarm com-
parator, and associated readout and control systems. 
The comparator consists of a regulated dc power 
supply with outputs of 10, 50, or 500 volts, a set of
ranging precision resistors, and a transistorized meter 
amplifier. An optical meter relay performs both the 
functions of resistance value readout and alarm. The 
unit has two modes of operation: manual and' auto-
matic. 
In the manual mode, any one pin may be selected 
by dialing the corresponding number on the point 
switch located on the control panel. This activates 
the corresponding matrix relay. The point under test 
then appears on the point identification indicator, and 
its resistance, in relation to the other pins, is displayed 
on the ohmmeter. 
In the automatic mode of operation, each pin within 
the preselected interval is subsequently referenced to 
all other pins which are grounded. If the resistance 
value falls below a preset resistance value, the scan is 
stopped by the comparator at the alarm point, a lamp 
in the check switch is lighted, and the point identifica-
tion indicator displays the pin number in question. 
NEW 	
(continued 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000260 2020-03-11T20:33:35+00:00Z
When the switch is depressed, the scan continues 
from the pin following the alarmed pin until either 
another alarmed pin or the end of the scan is reached. 
Notes: 
1. The tester can check 200 pins directly, or more by 
the use of suitable adapters, if required. The instru-
ment is compact, portable, mounted on wheels, and 
operates on 115 volt, 60 cycle power. 
2. Inquiries concerning this innovation may be di-
rected to:
AEC-NASA Space Nuclear Propulsion 
Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B67-10260
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: Michael Vuckovich and Jack Shaw

of the Westinghouse Astronuclear Laboratory

under contract to
Space Nuclear Propulsion Office 
(NUC-10068) 
Brief 67-10260	 Category 01


Tester automatically checks insulation of individual conductors in multiple-strand cables

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