Combined Use of the Generator for Propulsion and Ship-board Power with the DC/AC Power System
Combined Use of the Generator for propulsion and Ship-board power with the DC/AC power System
The agt Generator generates current with a frequency of 120 to 480 Hz, according to size . It is essentially more effective than any other Generator and additionally essentially more compact and lighter. The Generator is therefore the ideal solution. The AGT Generator is not suitable to supply current direct to the ac shipboard electrical circuit . This is, however, not a disadvantage, then the problem is solved The agt Generator generates current with a frequency of 120 to 480 Hz, according to size. It is therefore not suitable for providing power direct to the 230 volt/50 hz ac ship-board circuit. This problem has now been perfectly solved, by setting up an intermediate stage through an inverter, by which means the ship-board circuit current, either direct from the ac voltage, or indirect, via the 24 volt battery circuit, can be generated. (A 12 volt ship-board circuit can be used for a performance of approx 4 kW).
The electronic inverter has an efficiency level of up to 94%. A level of efficiency is achieved by this method, which, because of the improved efficiency of the agt Generator in comparison to a conventional generator, is even better than when the current in a conventional Generator is generated.
The DC/AC power System .
Use of a battery system is ideal for capacity of approximately 18 kW. The battery acts, fore-mostly, as a buffer, which supplies current immediately, if a consumer is connected in the ac circuit. The ac circuit has a stable electrical connection, as can be found in a house. The Generator starts automatically if the consumer exceeds a set limit. It is not the case of storing electrical energy in large amounts, as the agt Generator is always available to charge batteries.
A modern DC/AC inverter is just as safe and simple as use in a normal household.
Directions regarding Buffer Battery Current
For safety reasons, Fischer Panda restrict the size of current, n constant use, to 280 Amps. The system performance is restricted by the battery voltage.
The maximum for 12 volts is 4kW,
24Volts 8 kW
48 Volts 16kW.
The Panda agt Generator current, when it is running, is set to match the electrical drive requirements, supplies dc via the HTL charge converter. The voltage is controlled according to the battery characteristic at many stages, so that the values are compensated according to the battery temperature. The Generator must be run in a certain mode, in order to charge the batteries. By means of this setting, the electric drive and the battery can be supplied simultaneously. The performance for the drive is, naturally, limited in this situation.
The DC/AC Inverter
Fischer Panda recommends Victron products for the ship circuit. The Victron Phoenix inverter is available for all above named voltages from 12 to 48 Volts. The inverter attains 230 Volts ac (real Sinus) from the battery, with a level of efficiency of up to 96%. Up to 6 units can be connected in parallel to the Victron Phoenix inverter (total, up to 18 kVA).
The shipboard battery is charged automatically by the agt Generator
The shipboard battery is so efficiently charged by the agt generator, that it was until now not thought possible. The Generator does not run longer than is absolutely necessary. The savings in running hours is often greater than 70%. The agt Generator starts automatically, if the current at the battery exceeds a set value and immediately supports the battery. Current never flows from the battery, because the voltage always exceeds the battery system voltage, if the Generator is running. The inverter receives current direct from the Generator and the batteries are simultaneously charged. (It is permissible, by the way, to use the inverter without batteries, since the battery must be used as a capacitor).
The battery has a much increased life expectancy, if the DC/AC system is correctly set, than is the case under normal conditions, because the battery is kept free from all damaging influences, so that it is never overloaded, discharged and is not discharged by more than 40% in cyclic mode. A life expectancy of 10 years for a suitable battery is normal under these conditions.
Advantages of using the Generator at intervals:
An agt Generator is principally always suitable for supplying a dc voltage to charge a battery, via a HTL charging device in combination with a rectifier. The quality of the dc is especially high, since the output always has a 3 phase current with a relative high frequency up to 480 Hz, and120° offset phases. This dc has a very slight residual wave of less than 2%. This is ideal for charging the batteries. Consideration must, however, be given to the fact that the charging device, with regards to the input voltage, must be precisely tuned to the agt generator. Since the charge current of the HTL charging device is controlled through the E-Tec Generator control by the speed of the generator, the HTL charging device can only be connected, if the Generator voltage lies within the given range (window). There is a safety control which separates the charge converter from the generator, if the correct conditions do not prevail. This means the DE propulsion and the battery charging function can only be simultaneously used when the voltage is maintained by the generator. The charge converter is often designed as a two stage version, so that whilst cruising with a motor, or ferrying in a harbour, the best running results are attained, if the Generator is only loaded by the battery charge.
Limits of the system in combination with a weakly loaded machine: („light load“problems with Diesel motors).
Consideration must be given to the fact that the performance of the Generator in certain circumstances cannot be used ideally for all running states, so that a „light load“ situation can occur in the case of a Diesel motor, which should be avoided, if possible. It must be ensured that the Generator has the appropriate load, if power is to be supplied to the shipboard circuit with an agt generator. This depends upon the size of the generator. If a Generator is designed for propulsion, i.e. for a performance of 40 kW/3,000 rpm, the speed can only be reduced by approximately 1,000 rpm. This means the motor still has a potential performance of at least 8 to 10kW. In these circumstances, if the Generator is only loaded by 4 kW; it is not sufficient to ensure that the necessary running temperature produces complete combustion. The machine would have a great deal of wear under these constant “light load” situations and would produce over-proportionately more poisonous substances in the exhaust.
If necessary, a separate charging Generator must be used, if the consumption is minimal.
If board consumption is minimal, this can be so balanced by the correct battery combinations that the Generator running time is kept to a necessary limit. In certain circumstances, a separate Generator must be used to charge the batteries, in order to avoid the “light load” situation. This state can also be influenced, because as many consumers as possible are run simultaneously.
The Generator can also be set up so that several small units run in parallel for all systems that require a large Generator to meet the performance demands for DE propulsion, where a sensible combination solution is not possible.
Ref-Search:Fischer Panda Generator, Fischer Panda Genset, Fischer Panda Electricial Generator
9193AD2A4004F70AC1256E690070AEB8