HIGH VOLTAGE RELAYS
1kV to 300kV
1mA to 800 amps
12V to 250V DC, 24V to 480V 25-800Hz or air pressure 40-125 psi
Air insulated types for
isolating loads, tap selections, safety discharge & grounding to help
meet OSHA and other safety regulations. Ratings from 1mA to 800
amps continuous, to 100,000 amps capacitor discharge. Peak 1 minute
test voltages from 5kV to 300kV. Single or Multipole. Auxiliary
contacts are optional on all types. Options include latching,
extended life, and tungsten contacts available for high current
closing. DC, 25-800Hz & air pressure actuation available. Also
usable in oil or insulating gas with increased ratings.
115V, 60Hz actuators are standard for pull-in currents less than 10A.
Higher actuator voltages are recommended for pull-in currents over 10A to
minimize momentary voltage drop. It is recommended that source impedance
allow no more than 6% drop at the coil terminals during pull-in. Most
models can be supplied with actuators for 24V, 48V, 70V, 100V, 115V, 200V,
208V, 230V or 480V, and 60Hz or 50Hz power. 400Hz or 24V, 48V, 100V, 115V
or 125V DC actuators are available at additional cost. Latching type
actuators are also available requiring only momentary current. Special
actuators and relay drivers are available for high speed operation of 0.5
to 10 milliseconds, or delayed operation upon loss of power. Air or
hydraulic pressure actuated relays are available for applications
requiring complete electrical isolation of the actuator, very high contact
pressure for high current or very long strokes for higher withstand
voltage ratings. Electric motor actuators are also available for special
applications. A small PC board is available to be inserted at the coil
input which will eliminate AC HUM and prevent coil burn-out on failure to
Most of the Ross Engineering Corporation high voltage relays with ratings
through 60kV can be adjusted to be mounted in any attitude unless
otherwise indicated. Where maximum reliability, minimum noise (HUM),
minimum contact resistance, or minimum pull-in voltage is required,
consult the Applications Engineering Department for mounting
recommendations. Please specify mounting position; base down is standard
and will be optimum unless otherwise noted. Most of the Ross Engineering
Corporation solenoid operated high voltage relays with ratings of 70kV or
higher are designed to return to their normal position by gravity when the
actuator is de-energized. These relays must be mounted in the recommended
attitude. Ross Engineering Corporation switches operated by air or oil
pressure, or by electric motors, generally may be mounted in any attitude.
HIGH CURRENT CLOSING AND CONTINUOUS HOLDING CAPABILITIES
High contact closing force enables high momentary current closing
capabilities ranging from 10A to 50,000A. Special tungsten contacts are
available to increase momentary discharge current ratings by many times,
but with reduced continuous current ratings. Continuous current ratings
drop and contact resistance may increase with standard copper alloy
contacts when arcing occurs or in a dusty environment, therefore special
silver contacts are available to maintain continuous current ratings when
closing or opening under load.
CONTINUOUS CURRENT RATINGS
Continuous current ratings are as of new and clean condition for a maximum
of 40°C ambient at sea level. Relays are suitable up to 70°C ambient with
forced ventilation. Current ratings as specified are continuous for 60Hz
RMS and DC, but should be derated 3% per 1,000ft above sea level.
Continuous current ratings of standard copper alloy contacts are reduced
after arcing. Special silver contacts must be used where continuous
current is required after arcing if current ratings are to be maintained.
Type of application should be considered when determining current rating
required. In most cases, continuous currents for long time duty should not
be more than 3/4 the current rating of the new relay. In open industrial
or dusty atmosphere it may be necessary to derate by 50%, further if
arcing occurs unless silver insets are used. Some units can be used in
applications above 60Hz at reduced current and voltage ratings. All RF
applications should be submitted to our Applications Engineering
Department for review.
INTERRUPT AND CLOSE CURRENT RATINGS
These air insulated relays are not rated for current interrupting. Most
are capable of interrupting 10 milliamps or more depending on type of
wave, load, and recovery voltage. Much higher currents can be interrupted
in insulating gas or oil and with certain other applications and models.
High voltage air insulated relays can close on high short time capacitor
discharge currents and are rated for safety grounding or high current
capacitor dumping. They have long life and little or no maintenance in
these applications. Tungsten contacts are available for longer life
capacitor discharge use. Fail-safe grounding or shorting relays of this
type with fully visible contacts are ideally suited for use in all types
of power supplies. Relays, contactors and switches for higher interrupting
capabilities are covered in other brochures.
HIGH VOLTAGE PEAK TEST
Ratings are for air at 760mmHg, 20°C. Derate 3% per 1,000ft above sea
level. All peak test voltages are 1 minute 60Hz peak hold voltages, unless
otherwise noted. The first figure in the model number is the peak test
rating between open contacts. The number following the contact
configuration designation is the rated peak test voltage to ground. On
most non-spherical contacts, transient pulse withstand may be considerably
higher than the 60Hz test level. Actual flashover values, for spherical
types, are approximately 10% greater than rated peak test hold values for
DC, 60Hz, and most transients.
HIGH VOLTAGE OPERATE
The peak test rating of high voltage relays should be 1.2 to 5 times the
normal high voltage circuit operating voltage, depending upon the
application. For lower power systems, where transients are unlikely or
intermittent flashover is of no consequence, a safety factor of 1.2 to 1.5
may be suitable. For medium power systems, or where moderate transients
are likely, a safety factor of 1.5 to 3 is desirable and 2 to 3
recommended. For higher power systems, or where transient over-voltages are
expected, a safety factor of 2.5 to 5 should be considered and the factor
should be based on the maximum probable transient. The peak test voltage
to ground rating should be selected in the same way as is the contact to
contact value. If a value other than the published rating is required, it
can normally be supplied as an extra cost option. On most grounding
relays, even though one contact is grounded, the insulation to ground
should be 10kV to 40kV to prevent HV ground current from flowing in
solenoid circuits during capacitor discharge, or transients.
Standard insulation used on Ross Engineering Corporation high voltage
relays and switches is fire retardant FR-4, G-10 or G-11 Epoxy glass
laminate. G-7 silicone glass insulation is recommended as an extra cost
option for RF applications, particularly above 300kHz. It also may be
necessary to increase insulation length for RF Applications.
OIL OR GAS INSULATION
The voltage withstand value is at least doubled or tripled and the
interrupt capability is much greater when the relay is immersed in
insulating oil, fluid, or gas. No modification is necessary for operation
in an insulating gas atmosphere; however, oil or fluid immersion requires
modifications and is an extra cost option. For maximum performance in an
insulating medium, where high voltage is impressed directly across solid
insulation, it may be necessary to increase insulation length to prevent
puncture at levels above the test rating in air.
AUXILIARY CONTACTS SPDT
Auxiliary contacts are available on request on all relays. Most smaller
relays are optionally available with at least two 10A, 250V AC or 3A, 24V
DC auxiliaries. Larger units are available with at least two 15A, 480V AC
auxiliaries, and some have provision for as many as eight. 10A, 115V DC
auxiliaries are available interchangeably with the 15A, 480V AC units.
Oil-immersed relays require special auxiliaries. Optional auxiliary
contacts can indicate fully open or fully closed HV relay.
HELPS MEET REGULATIONS
OSHA and other safety regulations indicate safety grounding of all HV
power supplies and systems for personnel protection. Ross Engineering
helps meet these requirements with its line of high voltage grounding and
discharge relays and accessories.
RUGGED AND RELIABLE
Thousands of trouble free high voltage applications in the past 42 plus
years have established Ross Engineering Corporation's reputation for
dependable, quality engineered products. Fire retardant high strength
epoxy glass laminate insulation with a moisture resistant coating is
standard on most units. Heavy duty contacts, which are specially designed
to minimize corona, are made of highly conductive but weld resistant
alloys. Ross Relays are noted for their ability to withstand high shock
and vibration as well as other severe environmental conditions.
Simplicity of mechanical design and conservative stress levels result in
long trouble-free life. Contacts on most relays may be rotated to renew
the contact area, resulting in even longer service life.
Ross Engineering Corporation manufactures some of the most compact air
insulated high voltage relays available. The best qualities of mechanical
and electrical design are combined to create these highly efficient and
reliable relays with as many as six poles or more.
These may have high voltage at the HV contact area. Safe high voltage
procedures must be followed by personnel when close to any of these
relays. Clearances and grounding rules must be observed.
for reference only and are subject to change.
Contact Ross Engineering
Corp. for current information.