Relay consists of high voltage reed switch actuated by rotating permanent magnet mounted on stepper motor shaft, with actuation assembly isolated from high voltage circuit. Unit can be modified for use as double pole or double pole double throw latching relay and can be used in either air or vacuum

Lovell, R. R.

Renz, D. D.

Stevens, N. J.

English

NASA Technical Reports Server

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August 1974	 B74-10079 
NASA TECH BRIEF 
Lewis Research Center	 M 
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. 
Very High Voltage Latching Relay 
The Problem: 
To design a high voltage (20 KV DC) relay circuit that 
will hold in a latched position without the continuous 
application of electrical power or mechanical locking 
devices, and that operates with very low current leakage 
and will survive in a severe vibration environment. 
The Solution: 
A high voltage latching relay consisting of a high 
voltage reed switch actuated by a rotating permanent 
magnet mounted on the shaft of a stepper motor, with the 
actuation assembly isolated from the high voltage circuit.
How It's Done: 
The high voltage latching relay consists of a single pole, 
normally open, high voltage reed switch, and an actuation 
assembly (see photograph). The switch is mounted on 
38.1 mm (1 1h in) long by 6.35 mm (V4 in) diameter 
insulators attached to a fiberglas base plate. The actuation 
assembly, mounted on the baseplate beneath the switch, 
consists of a samarium-cobalt permanent magnet mounted 
on the shaft of a small 90 0 stepper motor. The actuation 
assembly is electrically isolated from the high voltage 
circuitry by ceramic insulators, the fIberglas baseplate, 
w %#(!.¼ over 
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.
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and a polyiniide plastic shield. The ceramic and fiberglas 
contribute high bulk and surface resistivities and 
comparatively long conductivity paths. The plastic shield 
effectively increases the spacing between the motor and 
the high voltage circuitry by increasing the gaseous 
conduction path length in air. 
The relay is closed by stepping the motor 900 which 
aligns the permanent magnet perpendicular to the switch. 
The switch resistance to ground is greater than 10 1 6 ohms 
and the power required to latch or unlatch the relay is 
peculiar to the stepper motor, e.g., 4.9 watts at .16 amps 
for actuation times up to ½ second. The switch is opened 
by stepping the motor back 90 0 to remove the magnetic 
field and allow the switch to return to its normally open 
position. The detent tojque in the stepper motor holds 
the magnet in position so that the only power required is 
that which steps the motor to the desired position. 
This relay has been successfully operated in vacuum in 
a 20 KV DC circuit with the actuation assembly at ground 
potential and has also been successfully flown on a space 
mission, fully meeting all requirements.
Notes: 
1. The unit can be modified for use as a double pole or 
double pole double throw latching relay. 
2. The latching relay can be used in either air or vacuum. 
3. This item should be of interest to manufacturers of 
ionized gas plasma equipment, medical electronic 
equipment, and communications equipment. 
4. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B74-10079 
Patent Status: 
NASA has decided not to apply for a patent. 
Source: R.R. Lovell, N.J. Stevens, 
and D.D. Renz
Lewis Research Center 
(LEW-12265)
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B74-10079	 Category 01


Very high voltage latching relay

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