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CE marking Low voltage directive: CEE 73/23 and CEE 93/68
Machine directives CEE 98/037 and CEE 98/79
Machine safety, section 1, general specifications CEI/EN 60204-1
Electromagnetic compatibility: CEE 89/336, CEE 92/31 and CEE 93/68
The VSS+ DC was originally developed in line with the numerous constraints imposed on the design of passenger vehicles. Numerous tests were carried out in the development stages to ensure that there would be no danger in the event of a major incident. The results of the tests were confirmed by UL and TUV laboratories.
The VSS+ DC systems have been designed to obtain 160 kW of power in the space of 12.5 seconds. With a load of 180 kW, the back-up time will be 5 seconds, for 145 kW: 15 seconds, 120 kW: 20 seconds, 60 kW: 40 seconds. To increase the power and reduce the back-up time, several VSS+ DC systems can be set up in parallel.
As a general rule, it takes approximately 2 minutes. The time depends on the power of the UPS charger. For certain applications, it is possible to obtain a back-up time of 20 seconds by adapting the UPS charger. If a fault occurs on the electrical grid during the recharging phase, the VSS+ DC will provide power with the energy available.
During tests, 8 VSS+ DC systems were set up to operate in parallel on the direct current bus of a unitary UPS. However, it is possible to increase this number according to power needs and redundancy.
The system is very quiet: the noise level is less than 45 dBA at 1 metre in normal operation.
Unlike batteries, it is easy to find out the charge status of the VSS+ DC. Available energy is proportional to the speed squared. Thus, when the flywheel is at full speed, the entire amount of energy is available. The information can be viewed on the LCD display.
Starting: 0 to 50 °C
Operating: - 20 to 50 °C
Storage: - 20 to 80 °C
The VSS+ DC can be controlled remotely via the local network or via a modem connected to a telephone line.
Flywheels can be placed into two categories depending on the speed of rotation.
Low-speed systems generally comprise steel flywheels which rotate at less than 10,000 revolutions/minute. The energy stored by the rotating weight is proportional to the speed squared; if the speed is increased, the rotating weight can be reduced.
The advantage of low-speed systems is that they have a relatively simple design. However, the power they produce is low in relation to their mass and they have numerous mechanical bearings which create friction which in turn consumes energy and reduces output.
The high-speed VSS+ DC systems employ a composite flywheel with magnetic levitation. The speed of rotation of the flywheel is greater than 50,000 revolutions/minute. The advantage is that a sizeable power is obtained for a low mass, it is very compact, there is no friction, output is higher and there is a reduced need for maintenance.
The VSS+ DC systems use cutting-edge technologies:
A high-speed carbon fibre flywheel
A magnetically-levitated rotating assembly
A built-in vacuum device
A synchronous generator motor
The rotating assembly rotates at more than 500,000 revolutions/minute.
One of the main advantages of the VSS+ DC compared to traditional flywheels is that the bearings (5 of them) are levitated. 2 radial bearings are used on the magnetic X axis, 2 on the Y axis, 1 on the Z axis in order to keep the rotary assembly levitated. There is no friction and therefore no losses and no requirement for bearings to be maintained.
One of the major advantages of the VSS+ DC over other flywheels is that no vacuum pumps are required.
The system that creates the vacuum, in the space where the inertia wheel rotates, is built into the rotary assembly; it does not require maintenance or replacement.
It maintains a constant vacuum, almost like in space, which is a million times lower than atmospheric pressure, removing nearly all aerodynamic resistance which in turn reduces losses. This systems removes the necessity for an external vacuum pump which consumes electrical energy, requires regular maintenance and which might need to be replaced.
The average consumption required to keep the VSS+ DC in operation is less than 300 Watts (less than 0.2% of 160 kW). This performance level is the product of the technology employed: operation in vacuum, magnetic bearings for operation with levitation, synchronous motor, cooling system which is activated when the temperature is high.