ATTACHMENT_1_ROTATING_FREQUENCY_CONVERTER_GENERATOR_SOW.pdf

STATEMENT OF WORK

ROTATING FREQUENCY CONVERTER

1. GENERAL DESCRIPTION

When aircraft are parked at airport terminal stands with their engines shut down they require a reliable and controlled supply of 400Hz power at 200V to be supplied from an external source.

This power is used to support the aircraft on-board electrical systems whilst the aircraft remains at the terminal. Since normal airport power supplies are only available at 50 or 60Hz it is necessary to provide a frequency converter to convert the supply to 400Hz.

The single cabinet of the converter machine will be located in the back where the switchboard with all control and monitoring components are placed in front of the machine.

The converter machine will be a brushless, single-frame converter where the motor and generator are accommodated in one housing on one common shaft. The fan for cooling the machine and the switchboard will be located on the converter shaft.

The converter motor will be connected directly to the normal supply system, started and run via a soft-starting device (choke, pony motor). At completion of the starting cycle the generator and the generator voltage, whose amplitude and frequency are constant, will be available to supply the load.

Correct operation of the system will be monitored by micro processors (voltage, temperature, etc.). In the event of a fault the system controller will react accordingly and protect both the converter and the connected load against possible damage.

Every stage of the converter operation will be monitored and controlled for correct operation and performance by high speed digital microprocessors control circuits, together with the appropriate software. This will ensure that the converter output is maintained within the stated frequency and voltage limits whatever the fluctuations to load and/or input supply.

Should a malfunction occur, an Event Memory will maintain a comprehensive record of the last 1200 operational events, which can be recalled via a mimic display panel in correct chronological order with date and clock time.

There will be a Control Panel on the front of the MG-Set cubicle which contains the mimic display with multi-aspect LED (light emitting diodes) indications, an 80-character LC (liquid crystal) display, on/off buttons, up and down buttons and enable and shift buttons

1.1 Performance under Unusual Conditions

Overload - The generator output current will depend on the load. High peak currents are possible (up to eight times the nominal current). If the output current is higher than the following values, the converter will be switched off after the given delay. In standard units the values are set at the following:

� Greater than 200% max. 120ms � up to 200% approx. 10 sec � up to 150% approx. 2 min � up to 120% approx. 10 min

At higher overloads the output voltage will fall below the permissible tolerance. The frequency converter will be switched off after one second at the latest.

Short-circuit on the load bus-bar - In principle, a short-circuit occurring on the output side is handled similar to an overload, except that the output voltage is very low. The converter is switched off after 120ms.

Mains fault - The frequency converter will detect problems with the incoming supply, and will cause the unit to switch off (after 50ms) or in case of standby, not to start - in this case the LEDs on the mimic display are off.

Failure inside the unit - In the event of an internal failure, the system cuts out to protect both the converter and the load.

Operation from a diesel gen-set - it is necessary to take into account the start phase and input current of the converter when designing the configuration for a gen-set.

1.2 Description of the system

The frequency converter will be designed to accept a 3-phase mains supply with or without a neutral.

There will be a filter at the converter input which limits the electrical emissions (RFI) back to the mains. Power switch Q100 supplies the entire control system.

The converter motor will be started via contactor K1, after which start motor main contactor K2 closes. When the motor reaches its rated speed, the exciter will be supplied by the voltage regulation. The generator will produce the output voltage and the outlet will be switched on via K6.

The System Controller monitors the mains voltage, input power, output voltage and current. It controls contactors K1, K2 and K6 and monitors the starting phase of the converter. All measured values are processed and displayed.

The generator compensation will maintain the output voltage in the right way to compensate the voltage drop along line.

An integrated control panel with push buttons and a LC-Display to operate the unit is located on the front door of the unit.

Every stage of the converter operation will be monitored and controlled for correct operation and performance by high speed digital micro-processors. Control circuits, together with the appropriate software, will ensure that the converter output is maintained within the stated voltage limits whatever the fluctuations to load and/or input supply.

1.3 System control

The System Controller Board will control all functions. All measurements are made via measurement boards. Board #1 will be used to measure the input current and voltage, Board #2 will be used to measure the output current and the output voltage at the output contactor, Board#3 will be used to measure the remote voltage. The controllers on the IO (Input/Output) board and on the optional Protocol Gateway will be controlled via a serial connection. A System Controller Board will have the function of complete system control (working like a PLC). In addition, every internal event will be recorded and saved by the Event Memory in chronological order. The Control Panel will consist of control and display elements for the user. Commands will be analyzed by the system controller and interpreted into actions. Measurement values for the input and output circuits will be processed and displayed.

1.3.1 System control components

In addition to the voltage regulator function already described, the system controller board (main controller) will handle the master system control function.

Control commands from the control will be transmitted to the main controller, evaluated and converted into the appropriate actions. Measured values will also be evaluated in the main controller displayed on the LC display mounted on the door. Operational signals will be displayed in the mimic diagram or recorded in a memory as events in correct chronological order with date and clock time. The events will be retrieved to the LC display or via the serial interface as required.

1.3.2 Monitoring and diagnostic system

In a Power System installation, the main task of the monitoring and diagnostic system is to support fault finding and fault clearance.The cause of the fault will be displayed in plain language on various screens. The data will also be transmitable via a modem link directly to the service center of the manufacturer, where experienced personnel provide fault diagnostic support.

The converter unit will be equipped with an RS 485 interface for a central monitoring station / controller and optionally with a modem interface (RS 232) for remote diagnostics. Provision is made for a fault alarm printer to be connected to the modem interface.

The Control Panel will give the user a comprehensive status indication of the frequency converter. The LEDs on the mimic display show the status of each logical section of the converter, displaying green, yellow or red, and flashing or steady state to show various normal, available, warning and abnormal states of the converter. The push buttons will allow the user to switch the unit on and off.

With push buttons “UP arrow“ and “DOWN arrow“, input and output voltage, and input and output current will be displayed for each phase. Additionally, frequency and load will also appear on display.

For remote indication, six potential-free contacts (change-over type) will be provided on the customer interface card, which can be programmed on the control panel for operational and fault signals as required. Fault alarms are capable of being connected via potential-free contacts to the central building monitoring. The individual fault alarms will be freely programmable.

The System Controller Board will handle the master system control function. Control commands from the control panel CP are transmitted to this controller, evaluated and converted into the appropriate actions. Current operating parameters (measured values etc.) will be also evaluated by the System Controller Board and sent back to the CP, to displays them via the LC Display.

The following measurement values are not only displayed, but are also monitored for deviations from the specification:

Input under & over-voltage

Input under & over-frequency

Input phase rotation Input overload

Output under & over-voltage Output under & over-frequency Output phase rotation

Output overload

Over-temperature

The generator frequency converters w i l l have two different kinds of voltage drop compensation available as a standard feature. One will be a remote voltage sensing and regulation system which uses control wires connected to the three phase and neutral pins from the plug. The plug sends it’s voltage signals to the unit’s voltage compensator controller, which compares them with the voltage readings just prior to the output contactor of the unit and then automatically adjusts the output voltage accordingly, to overcome the voltage drop created by the output cables. The second will be the generator compensation. The generator will automatically adjust the output voltage throughout the full output kVA and power factor rated range to accommodate the wire characteristics installed. The generator system will use software and current transformers to provide the voltage drop compensation automatically

1.4 CONTROL PANEL

The Mimic Display on the Control Panel will give the user a quick and comprehensive status indication of the frequency converter.

2 DESIGN AND CONSTRUCTION

2.1 General

All printed circuit boards will be suitably coated to protect against the effects of humidity, corrosion and salt laden atmosphere. All integrated circuits will be installed in plug-in sockets to simplify repair. All major components and sub-assemblies will be labled with an identification number

2.2 Cabinet

The cabinet enclosure will be designed to be suitable for the intended environmental conditions. The cabinet will be mounted in such manner that no damage will occur as a result of transportation. The complete frequency changer will be designed for lifting and transporting by fork-lift.

The control panel will be part of the converter cabinet. Provisions will also include a remote control panel.

2.3 Finishes

The surfaces will be primed and finished with 2 top coats. Unless otherwise specified, color or finishes are manufacturer’s standard.

Color of exposed surfaces of frequency converters installed on passenger loading bridges shall match the adjacent surfaces of such bridges.

Type of cabinet: modified Rittal series Material: Metal steel sheet, 2,0 mm, mounting tray: 3,0 mm Surface: dip primed and powder sprayed; RAL 7032 Mounting tray: zink coated Ingress protection: IP 43 for indoor use IP 54 for outdoor use

3 ELECTRICAL CONNECTIONS

3.1 Cable sizing

Cables should be sized in accordance with the rating of the next protective device upstream, taking into account temperature, volt-drop and installation method factors, as per the appropriate standard for the site.

3.2 Mains fuses

To meet Health & Safety requirements, lockable isolating fused-switches will always be installed for the mains infeed. The fuses should be of type GL. Likewise, it should be possible to isolate the converter output from downstream circuits by means of an external lockable switch or circuit breaker.

3.3 Connections

Power:

3 phase Mains Supply + Neutral + PE

3 phase 400Hz output + Neutral

Controls:

Connections to the converter will include most of the following, depending on the configuration of the system External Voltage Monitoring

Parallel Controls between converters

Central Control Functions

Remote Indications

Emergency Stop circuit