The experiment and the technical skill with your service.
Since 1938, Métal Deployed Resistor is based in Montbard close of Dijon in Bourgogne. Its constant step of quality and optimization of its organization allows Métal Deployed Resistor to answer more close with the needs for its customers. Today, a team of 56 people including 25 ingénieurs and technicians are with your listening and act in the following fields: Design, Research and Development, Manufacture, Tests, Forwarding and Service After Sale of electric resistances of power.
Our various applications :
Energy : - earthing, - filtering, - integration of related components to the resistance of power (disconnecting switches, switches, crossings, TC...) engine control : - for engine D.C. current , - stator, - resistances of excitation, discharges, ... - braking (lifting, translation, direction), - electrical equipment boxes.
Vectrohm : - démarreurs électrolytiques, - consumable, - parts spare.
Charge : - bancs of load natural convection, - charging benches forced ventilation (tunnel of charge) - bancs of discharge, battery and load D.C.current, - specific load of test, - control, regulation, electrical equipment box.
Railway resistance of traction (rheostats of braking and resistances auxiliary) : - first goes up, - restoration.
In the load banks for generating sets, the resistors are used when the generator is running at low power to prevent the diesel engines from gumming up. The use of industrial resistors as load banks is also a standard practice to maintain batteries in electrical laboratories and industrial testing facilities.
We can propose inductive load banks able to vary the power from 0.8 to 1.
Simulation of the load of radio transmitters. Forced ventilation resistors 500 kW BBC (Switzerland)
Compact, ergonomic, silent, modular, the new models of our wide range have even more improved their reliability which has made the reputation of METAL DEPLOYE RESISTOR for 50 years.
STANDARD PRODUCTS
Natural cooling 15 kW under 400V
NATURAL SERIE :
. Natural air cooling, . Power from 5 to 120 kW under 400 V 3 phases, . Connection in low part (cold area), . Protection level IP13 (outdoor normal use), . Options : terminals bar (DIN), IP23, castor wheels.
100 kW and 400 kW under 400 V 3 phases - Forced air cooling
AIR COOLING SERIE 400, 700 AND 800 :
. Horizontal forced air cooling. . Power from 50 to 1200 kW under 400 V 3 phases . Helical fan with 400 V motor IP54. . Air flow control by switch. . Options : terminals bar on side, castor wheels, double insulation.
SPECIFIC PRODUCTS
BANC DE CHARGE 21 MW
Our technical know-how and means (CAD, finite elements calculation, internal laboratory for heating and vibration) enable us to design customized equipments : . load resistor type "Tunnel" (beside) in air flow duct, . High voltage and high frequency, . Vertical forced cooling, . Reactive additional load, . Control module for switching, automatic regulation.
For more details, please contact us or ask us to get an estimate.
Compact, ergonomic, silent, modular, the new models of our wide range have even more improved their reliability which has made the reputation of METAL DEPLOYE SA for 50 years.
STANDARD PRODUCTS
15kW under 400V natural convection 100kW and 400kW under 400V forced ventilation
USE :
Load bank : to prevent damage to the diesel engine, the resistive load maintains a minimum load on generators of 25 %
Testing bank : for type or periodic testing of UPS systems and battery
NATURAL SERIE :
Natural air cooling
Power from 5 to 125 kW
Connection in low part (cold area)
Protection level IP 13 (outdoor normal use)
Options : terminals bar (DIN), IP 23, castor wheels
AIR COOLING SERIE 400, 700 and 800
Horizontal forced air cooling
Power from 50 to 1200 kW 3 phases
Helical fan with 400V motor IP 54
Air flow control by switch
Options : terminals bar on side, castor wheels, double insulation, control cubicles
SPECIFIC PRODUCTS
Charge Tunnel 40 kW 400 V
Our technical know-how and means (CAD, finite elements calculation, internal laboratory for heating and vibration) enable us to design customized equipment :
load resistor type "Tunnel" (beside) in air flow duct
high voltage and high frequency
vertical forced cooling
reactive additional load
control module for switching, automatic regulation
TECHNOLOGY :
Grids manufactured in expanded metal sheet type Gridex U, N or F made of stainless steel : low self inductance and excellent ability to withstand vibration and pollution
Enclosure in galvanized steel sheet with stainless steel bolts : high resistance to corrosion and shocks
Gridex U: For standard applications, no matter whether the period of operation is short or long, Gridex U resistors combine the thermal capacity of Gridex G resistors and the technical characteristics of Gridex N and F resistors, although their design is less complicated. Gridex U resistors consist of solid strips, extra-extended diamond meshes and lateral stiffeners.
Gridex N & F: When the current transit through the resistor provokes heat dissipation into the surrounding environment (non-adiabatic heating), the resistor must be designed to optimize heat exchanges. This is the case of Gridex N and F resistors. Gridex N resistors are intended for natural ventilation, Gridex F resistors for forced ventilation.
Gridex G: When a resistor does not produce any significant heat exchange with the surrounding environment (adiabatic heating) when heated, it should have as great a mass as possible. This is the case of Gridex G resistors, which consist of steel sheetmetal elements cut into rectangles and mounted in staggered configuration.
Gridex T: The Gridex T resistors are made of woven resistive elements. The chain warp thread wire is not conductive, the weft thread is resistive . This technology allows high resistance values (reaching hundreds of ohms) and can be adapted to high voltage application (continuous or transient)
LIQUID RHEOSTATS
Vectrostar R : The Vectrohm electrolytic staters are rheostats that always work in the liquid phase. This technology provides a continuous and progressive variation of the Resistance value.Therefore, motors are started very softly using these resistors
Reliability and strengh for starting and braking...
Resistors have a strategic place in the control of Power Electric Motors. Their advantage is to limit the starting current of all kinds of applications, but they also smooth the mechanical shocks and in some heavy duty application, they can provide a start where other types of starting devices could not make it possible. Simplicity, reliability and strength, such are the advantages of metallic and liquid rheostats frequently used with electronic systems.
Motor control on container carrier Port-Bou (Spain)
For Electrical locomotives, the braking is achieved by both mechanical brakes (drums & disks) and electrical brakes, which are most of the time rheostatic with high-performance resistors. Gridex resistors equip the French ultra-high speed train TGV which must use a powerful braking system, and many types of trains which have various braking cycles.
Today
several electrical
equipments generate current distortions in networks. Those distortions,
named harmonics, can be modelized as a collection of sinus current at
different frequencies and amplitudes added to the basic network
current. They cause many different sorts of problems, such as :
- Increased losses,
- Malfunctioning of control system,
- High currents in phase and neutral.
Filtering resistor
130 kW pt - 347 ohms
Power
harmonic filters
are built up from passive LC components (i.e. reactors and capacitors
tuned in order to shunt off most of harmonics. The addition of a
resistor allows :
-
more precision in the original adjustment of the filters, -
Stretching of the effective bandwidth, -
Dituning due to fluctuations in components (owing to temperature).
DESIGNING OF POWER
RESISTORS FOR HARMONIC
FILTER
1.
Power dissipation :
This
power is partially stored in the metal or the material of the
heating element. The non stored power has to be transferred to the
surroundings either by radiation or by convection which depends on :
-
the design of the resistors, -
the surface of the heating elements, -
the temperature difference between ambient air and the heating
elements.
2.
Résistance value : Customer
requirements must imperatively indicate the nominal value of
the resistor.
3.
Voltage resistance : The
resistor must be designed in
accordance with various limits
(grid-banks - enclosures, arcing distances, creepage distances, BIL
withstandings).
4.
Current resistance : Connections
have to be carefully designed and examined because the
interventions of high current transients can create undesirable
electromagnetic forces.
5.
Miscellaneous : Environmental
and site conditions (pollution degree, sismic level,
corrosive ambient, wind, altitude).
To
check the
caracteristics necessary for the calculation of your resistor, please
consult our technical data available in the section "PRODUCTS
DOCUMENTATION" or ask us for an estimate.
Most power distribution networks have their neutral earthed to support important currents whenever a fault happens.
In order to avoid the damages and disturbances such faults can provoke, a resistor is fitted between the neutral and the earth to limit this current and to give electrical protection devices enough time to react.
Various and modular range :
Our experience acquired through the design and supply of thousands of METAL DEPLOYE resistors all over the world, the flexibility of our technology and the robustness of our products allow us to meet the more various requirements. We can design any tailor-made solution.
The range of resistors already manufactured :
- Electrical criteria :
Rated fault current : from 5 to more than 5000 A.
Rated voltage : from 0.38 to 500 kV.
Rated time : from 1 sec. to continuous time rating.
- Mecanical criteria :
Direct connection or through top or side mounted bushing.
Protection degree of housing : from IP00 to IP54 (we recommend IP23)
Finishing : hot dip galvanized, painted, stainless steel housing or other if required by customer.
- Options :
Current transformer HV or LV.,
ON or OFF load disconnecting switches,
Space heater,
Elevating stands,
Bushing cable boxes.
To meet the client requirements, we have designed and supplied disconnecting and change over switch cabinets including disconnectors and current transformers for direct earthing or earthing through the Neutral Earthing Resistor.
Thanks to the VECTROSTAR R principle, the user obtains the maximum torque at very low speed (starting of locked and loaded machines can be accomplished). Start-up current for slip-ring motors from 0,5 to 1,5 rated current in.
PERFORMANCES
Drastic decrease in start-up overcurrent.
Adjustement of maximum torque with minimum current.
Suppression of mechanical shocks through a constant acceleration torque and progressive speed increase.
Enables a number of start-ups in a row without any possible damage to the resistivity.
Suitable for a wide range of motors allowing motor and machines changes
ADVANTAGES - SMOOTHESS
The continuous and controlled decrease in rotor resistance provides start-ups without mechanical snatches.
ADAPTABILITY
The dosage of the electrolyte allows a perfect adaptation of VECTROSTAR R to the operating environment of the motor (resistant torque, inertia, load, etc...). The duration of the start-up depends on the dosage of the electrolyte, as well as on the adjustment of the flow valve which controls the electrolyte flow entering the start-up tank.
CONSISTENCY
The electrolyte reserve tank is large enough to allow an efficient circulation into the start-up upper tank. Subsequent start-ups can be made without changing their characteristics.
SECURITY
The VECTROSTAR R envelope provides an electrical insulation, except for Vectrostar from R 1500 up to R 4000 which have to be earth connected). A thermostat monitors the electrolyte temperature inside the start-up tanks.
ROBUSTNESS
IP 569 protection, corrosion resistant equipment, limited maintenance is required. The starters from Vectrostar R 1500 to R 4000 are built in stainless stell. 5AISI 304L as a standard).
RELIABILITY AND MAINTENANCE
Low operating temperature minimizes electrolytic fluid maintenance.
Anti-corrosive electrodes eliminate oxidation and breakage.
Unit can be installed in any location. Harsh environments are not a problem.
Standard unit controls permit full automation of start-ups.
ECONOMICAL
Installation flexibility and low maintenance make the VECTROSTAR very economical.
SELECTION CHART
STARTER
R25
R65
R120
R200
R200P
R200T
R800
R1500
R4000
Slipring motor (kW) Loaded start-up Unloaded start-up
40 50
90 110
160 200
300 355
600 650
900 1000
900 1000
2200 2800
4000 5000
AND UP TO 6000 kW ON REQUEST - R1500P - R2500P - R4000 - R4000P
Rotor voltage indicative (Volts)
600
600
800
800
800
850
850
2000
3000
VECTROSTAR R : ELECTRICAL DIAGRAM
This electrical diagram is not exhaustive. We can propose different options and supply the specific electrical diagram you could require.
Dehydration of alfalfa of an agricultural cooperative. Puiss. 16 MW. Flow 65 tonnes/h of a air-steamer mixture of water with 700°C
The use of expanded metal resistances of weak thermal inertia makes it possible to heat with a high degree of accuracy and without polluting it an intended gas, for example, to dehydrate medicinal or chemical foodstuffs.
It is for these reasons even as new industries turn to the resistance heating.
By their nature and their function, the electrical grids are often the object of fortuitous defects. It is thus essential to install protection systems. This protection depends on the treatment of the neutral which can be done in three different ways:
Insulated neutral (fig.1) - This technique which induces important risks in the event of earthing of a phase is used only on networks of small size and weak tension .
Earthing direct of the neutral (fig.2) - The neutral of the system is directly connected to the ground. In such a case, the current of short-circuit can reach 20 to 30 times the value of the rated current.
Earthing of the neutral with limitation of the fault current (fig.3) - This technique consists in inserting an impedance between the neutral and the ground. There are 3 types of impedances :
Résistance
Réactance
Wind of extinction of arc (winds of Petersen)
Of these three methods, only that using a resistance allows a detection simple and fast defect, while offering a potential of reference of which stability is suitable, the control of the current of short-circuit artificially created and a maximum safety for the environnement.
CALCULATION AND DIMENSIONING
The calculation of a resistance of earthing is done starting from the three criteria according to :
t (en s.) duration of the defect
U (en V) tension made up of the network
I (en A) intensity of the current crossing resistance during the defect
One deduces the value from it from resistance by the formula:
The mass of resistance is then obtained by calculating its adiabatic heating lasting the defect thanks to the simplified equation :
All our resistances of earthing are conceived in respect of the standards lEEE32-1972 and lEC289 which defines an acceptable maximum temperature of resistance according to the duration of the defect. This temperature for resistant stainless elements is of 760°C for a defect of duration lower or equal to 600 seconds and of 385°C for a defect of higher duration.
This technology enables to propose Power Resistors with high Resistance values (up to several hundred ohms).
Moreover, these resistors are particularly well adapted to applications requiring high voltages (continuous and transitory).
THE RESISTIVE WIRE
It is the woof of the mat. The wire diameter can vary from 0.3 to 2mm.Various alloys are available as standards (from Konstantan which has a zero temperature coefficient, to stainless; steel type alloy or iron-chrome-aluminum). The P distance (Fig 1) varies accordingly to the wires nature and diameter, and is usually between 1 and 5 mm.
THE CHAIN WIRE
It has to maintain the resistive wire as well as to keep an optimum coefficient of thermal exchange. A E class fiberglass is proposed as a standard. It presents the following advantages:
high temperature withstanding :
above 450'C for short time ratings
low coefficient of linear thermal dilatation. The mats have a low length variation according to temperature which makes the fixation simple.
excellent hot mechanical tensile stress resistance,
strong resistance to pollution (except fluorine pollution).
A wide range of materials (cotton, kevlar, silica fiber) can be proposed for specific applications.
DIMENSION AND DESIGN
The weaving process provides a large flexibility in the choice of the L and 1 dimensions.
However, in order to rationalize our products, we propose 2 standard widths :160 mm and 250 mm.
The plain strips at the ends are used for mechanical fixation and can also take part to the electrical insulation.
We currently use two different arrangements (Fig.2) : the mats can be used as independent resistors, either fixed between 2 supports ensuring the insulation, or in a " U " form , or rolled, to give them a sufficient inertia, in order to be self standing. In most cases, they are used in banks and connected in series or in parallel, or in a combination of both.
APPLICATIONS
harmonics filter
Resistor
low discharge of high voltage capacitors
infrared heating
they are also dedicated to applications where space limitations necessitate a specific and sometimes complex mechanical design. This occurs in small heating units.
After being cut out, the consecutive bands of a grid are alternatively separated and insulated from each other by an internal separator consisting of a box or stainless steel flanked by two sheets of mica.
GRIDS ASSEMBLY
The grids with their internal separator are screwed on two tie-rods and insulated from each other by external separators, themselves attached to two mica sheets. The tie-rods are insulated by a mica grommet. The stacking thus obtained, after treatment in a steam bath, is press-clamped to form a compact battery.
GRIDES CONNECTION
Continuity of the electrical circuit is obtained by spotwelding the end bands of the consecutive grids. The junctions are designed to act as taps, to which it is possible to connect screw and nut. Finally, the ends band are twisted, to prevent any possibility of contact between them. The Gridex G, thus assembled, makes a sturdy, stainless steel unit which is maintenance free and easy to connect.
APPLICATION
Rheostatic control starting resistors for slip ring motor or squirel cage motor
The Gridex N (Natural convection cooling) or Gridex F (Air forced cooling) use precision cut expanded metal as resistances elements. These elements feature accurately controlled mesh having solid, integral ends for mouting and connection.
DESIGNING OF ELEMENTS
Type of mesh There are two basic mesh designs : open mesh : for low resistance values, closed mesh : for high resistance values.
Resistance elements Two basic designs : flat elements, C (or Grider) elements. The choice of design is based on resistance value, cooling requirement and mechanical rigidity.
Assembly of resistance elements Resistance elements are stadked together on stainless steel threaded rods, the connection on each element to its neighbor is made by hot spot welding.
Insulation the insulation between resistance elements themselves and rods is made by :
ceramic rings as standard application
mica tube and washers to prevent vibration, trepidation (this method is mostly used for dynamic braking or railway resistor applications).
Heat dissipation the precision cut expanded metal resistance elements; provide a maximum heat dissipation surface either through natural convection or air forced cooling.
Resistance value precision the precision cut expanded metal sheet technique can provide required resistance value with low tolerance by varying the dimensions of the mesh.
Flexibility the flexibility of expanded metal resistance allows in most cases to fit with restricted available space as well as to optimize the weight i.e. providing low weight with low cost per kW for continuous rating and if necessary high weight grids for difficult cycles.
APPLICATIONS
Dynamic braking resistor (air forced or natural cooling).
High fault current or high voltage Neutral Earthing Resistor.
High power and high voltage harmonics filter resistorLoad banks.
Heating.
ALLOYS
The different type of used alloys are : Nickel Chromium stainless steel (18% Cr, 10% Ni, AISI 304, 20% Cr, 32% Ni 32/20, 20% Cr, 63% Ni 63/20)
Resistant elements attached mechanically by solid bands that are at relatively low temperature compared to the active part.
An increased service life for the resistant elements as well as holding and insulating parts. Moreover, the mechanical studiness of assemblies is preserved.
DESCRIPTION
The Gridex U system is made from collections of expanded metal grids (RU) edged :
on the two short sides, by adhering solid band designed for mechanical attachment and for the electrical connections,
on the two long sides by U section stainless-steel stiffeners. A flexible insulating tape (mica paper) housed inside the stiffener, whilst considerably protruding, provides insulation between the latter and the edge of the grid.
ASSEMBLY
Grids are stacked together on two steel tie rods threaded at th ends. Insulation between the grids and between grids and rods is obtained by shouldered ceramic rings. The assembly is locked by nuts and "contact washers".
CONNECTIONS
The connection between grids designed to ensure continuity of the electrical circuit are obtained by a stainless steel jumper hot spot welded to consecutive grids. Welded jumpers confer excellent mechanical rigidity of the whole unit. They are duplicated in case of high current.
RANGE
Gridex U Grids design allow us to obtain different types of grids with standard dimensions (180 x 360) with resistance values varying from 0.0114 à 12.7 ohms according to the grid thickness (from 0.4 to 3 mm) or resistance material alloy of mesh type. Each grid can withstand 600V or 1.2 kV BIL
APPLICATIONS
Neutral Earthing Resistor
Harmonics filter for SVC or HVDC Sub-stations
Load banks
Rheostatic control
ALLOYS
The different type of used alloys are :
Nickel chromium stainless steel (18% Cr, 10% Ni AISI 304, 20% Cr, 32% Ni 32/20)
In today's electrical system, several types of common equipment generate current distortion's in any electrical network. Those distortions, named harmonics, can be modelized as a collection of sinus current at different frequencies and amplitudes added to the basic network current. They cause many different sorts of problem, such as :
Increased losses.
Malfunctioning of control system.
High currents in neutral phase and neutral.
Resonance problems.
Interface with telecommunications.
Interface with computer traffic.
>Further more, modern electrical equipment impose stringent demands on voltage stability and curve shape. Therefore, today's industrial system's and power-distribution network need harmonics filters to have low distortion values and be free from harmonics.
Power harmonics filters are built up from passive RLC components, i.e. resistors, reactors and capacitors which are sized so that they together form a tuned circuit.
Basicaly harmonics filters are built up from a passive LC components (i.e. reactors and capacitors) which are sized in order to shunt off most of harmonics. However, it is never possible to adjust a filter precisely. There are three reasons for this : lack of precision in the original adjustment, possibility of fluctuation in the supply frequency, change in capacitance due to temperature variations. As a result, each filter has an additional resistor which serves to increase the effective bandwidth and make it steadier and easier to adjust.
DESIGNING OF POWER RESISTORS FOR HARMONICS FILTER
The filter resistor as other components of filter (Capacitor, Reactor) must withstand the same stress in terms of voltage, of current and environment conditions with in addition, a thermal stress due to energy dissipation.
This energy is a combination of a permanent (rms) current flow and from time to time of an additionnal overload as a result of a temporary extra current flow.
The variation between Resistance value at ambient temperature and resistance value at operating temperature depends on the Resistance coefficient of the material used.
The temperature of resistor must be limited, so as not destroy resistor or components.
The limitation of temperature to a reasonable limit threshold is therefore an imperative requirement obtained differently according to the partiicular application.
The designing of resistors for harmonics is based on :
Power dissipation Chis power is partially stored in the metal or the material of the heating element.
The non stored power has to be transferred to the surroundings either by radiation or by convection which depends on :
The design of the resistor.
The surface of the heating elements.
The temperature difference between ambient air and the heating elements.
Resistance value When a resistor is designed from the thermal point of view, the resistance value has to be achieved to adapt the resistor to the required power supply.
Voltage resistance The resistor must be design in accordance with various limits (grid-banks - enclosures).
Current resistance Connections have to be carefully designed and examined because the intervention of high current transients can create undesirable electromagnetic forces.
This is the most common, economical and sufficient solution. It is used when the neutral of the supply transformer is available and its own impedance is not enough to limit the fault current.
There are different resistance material used to build a Neutral Earthing Resistor:
cast iron resistance elements : fragile, no corrosion resistance
liquid resistor : old technology, maintenance problems due to evaporation or freezing of electrolyze.
Neutral Earthing Resistors made from stainless steal are the best technical and economical solution.
Range
Electrical criteria Rated fault current : from 5 to 5000 A. Rated voltage : from 0.38 to 500 kV. Rated time : from 1 sec to continuous time rating.
Mechanical criteria Direct connection or through top or side mounted bushing. Protection degree of housing : from IP 00 to IP 54 (recommended IP23). Finishing: hot dip galvanized, painted or stainless steel housing.
Options Current transformer HV or LV. ON or OFF load disconnecting switches. Space heater. Elevating stands.
Technologies used
GRIDEX N
GRIDEX U
GRIDEX
Special construction :
To meet the client requirements, we have designed and supplied disconnecting and change aver switch cabinets comprising disconnectors and current transformers for direct earthing through the Neutral Earthing Resistor.
Dehydration of alfalfa of an agricultural cooperative. Puiss. 16 MW. Débit 65 tonnes/h of a air-steamer mixture of water with 700°C
The use of expanded metal resistances of weak thermal inertia makes it possible to heat with a high degree of accuracy and without polluting it an intended gas, for example, to dehydrate medicinal or chemical foodstuffs.
It is for these reasons even as new industries turn to the resistance heating.
The general purpose of earthing is to protect life and property in the event of 50/60 Hz faults (short circuit) and transient phenomena (lightning switching operations). The question of how a e/stern shall be earthed is designed by regulation. The regulation that one point of every system shall be earthed is designed primarily to preserve the security of the system by ensuring that the potential on each conductor is restricted to such a value as is consistent with the level of insulation applied.
The choice of the earthing method is based on the following criteria :
Voltage level : the insulation level of material must be in accordance with the induced voltage at the time of fault.
Insulation co-ordination.
Limitation of fault current : to reduce the electrodynamics stresses on material, to limit the induced voltage on telecommunications lines and over voltage on LV components.
There are 3 methods of neutral earthing:
Insulated neutral system (fig.1)
Direct earthing or solidely earthedx (fig.2)
Impedance earthing (fig.3) - The purpose of this method is to limit the current for greater safety.
There are 3 type of impedance earthing:
Earthing through reactance.
Earthing through ARC - Suppression coil.
Earthing through resistor.
CALCULATION OF NEUTRAL EARTHING RESISTOR
These parameters are needed to specify the earthing resistor:
U : Rated voltage line to line voltage or system voltage (kV)
If : Rated fault current (A)
T s : Rated time (Sec) - Duration of the fault
Resistance value :
When the flow of an electric current through a resistor is relatively short, dissipation is negligible and the heating temperature of that resistor depends on its capacity to store the electric energy (i.e. its heat value itself) in proportion to the mass and specific heat of the material used.
The rise in the resistors temperature will be provided by the relation :
When large-scale masses and energies are involved, the real resistance value of the resistor is taken into account, because it varies with the temperature which itself depends on the current flow, time. With that method of calculation we can determine the exact dimensions of the resistor to be built. For resistors heating adiabatically, masses as high as possible are therefore required.
As per IEEE-32 for neutral earthing resistor made from stainless; steel resistance material, the allowable temperature rise for 10,30 or 60 sec time rating is 760°K, 610°K for extended time rating and 385°K for continuous rating.
Dissipation of energy generated by asynchronous squirrel cage motors which are controlled by speed variable drives.
Control cabinets
Fabrication of short-circuiting cabinets associated to the starting resistors. The control box allows the successive short-circuiting of resistors steps with power contractors, the working order is given by the line contactor of the customer (startor). Additional services can be supplied on request.
. An integrated designing team composed of graduate engineers who knows the industrial context in which the resistors will be installed.
Laboratoire d'essais et R. & D.
. With an organization structured and effective whose essential objective is the satisfaction of our customers, from the study to the delivery.
. With our applied research laboratory, nwe are able to perform thermal and mechanical tests as well as to get
electric and dielectric measurements up to 150 kV. All our resistors
are final-checked on a test bank.
Awarded ISO 9001, by the AFAQ (French Institute for Quality), our resistors are controlled from the design to the commissioning with our quality procedure system.
Due to this innovative policy, our existing products are always improved and we are able to develop new fields of applications.
All our resistors are final-checked on a test bank. Besides these routine tests, we are able to perform type tests.
Our quality procédures and our internal management allow us to meet the needs of our customers.
Lightning impulse on a filter resistor. HVDC continuous current link between Denmark and Germany.
Insulated neutral (fig.1) - This technique which induces important risks in the event of earthing of a phase is used only on networks of small size and weak tension . 
Earthing direct of the neutral (fig.2) - The neutral of the system is directly connected to the ground. In such a case, the current of short-circuit can reach 20 to 30 times the value of the rated current.
Earthing of the neutral with limitation of the fault current (fig.3) - This technique consists in inserting an impedance between the neutral and the ground. There are 3 types of impedances :
