NFA-06.05 Multidisc Neutron Velocity Selector Controller
The microprocessor-based control electronic consists of a rotation speed controller connected to a safety-monitoring unit.
The main tasks of the control electronic:
Several safety functions are considered to prevent failures in operation or damage to the selector. In case of emergency, i.e. failure of any function of the selector the monitor stages switch-off the driving motor in order to stop the rotor.
The measuring channels belonging to the selector controller are the followings:
The functions of this channel are:
Due to the magnetic shaft coupling the rotation speed of both the motor and the selector rotor should be measured. The magnetic revolution number sensor on the driver motor shaft gives MRS(M) signals of 10 sine waves per revolution with amplitudes that depend on the rotation speed. The magnetic revolution sensor on rotor shaft gives MRS(N) signal. The frequency and amplitude of MRS(N) signal are the same of MRS(M) signal.
The MRS(M) and MRS(N) signals of revolution sensors are led to signal conditioner of the NFI-07.07 type PLL Controller module. It forms TTL pulses for the data acquisition. The pulses of revolution sensors are counted and displayed every 1 seconds by the built-in microcomputer consisting of NFI-09.02 CPU and NFI-09.03 Digital I/0 units. Also the microcomputer forms the MC control signals for the NFL-07.07 type power stage on the principle of PID algorithm. Because of the characteristics of asynchronous motor, both the frequency and the amplitude of the motor supply voltage have to be controlled. For this purpose a special PLL controlled switching mode power stage is used. The PLL circuit controls the motor frequency of the driving signal as its amplitude is modified through the duty cycle of switched transistor (PWM). (More detailed description in NFL-07.07 manual.) The rotation speed of the motor computed from the MRS(M) signal is compared to the rotation speed of the selector originating from the MRS (N) signal. When the magnetic shaft coupling becomes disconnected, the rotation speed of the motor is significantly greater than the selector rotor. In this case the magnetic shaft-coupling monitor stops the motor through NFL-07.07 unit. If the rotation speed of the motor becomes too high (over 7300 rpm) the rotation speed limit monitor stops the motor.
Because of the vacuum, no lubricated bearings has to be used the temperature of which should continuously be monitored. The L05073M0 type temperature sensors were placed in the bearing housings. The Rset resistance determining the sensitivity of the sensor is also here. A 1 oC change in temperature should correspond to a 1 µA change in current. The NFI-07.06 type Sensor Interface unit receives the TS(M) and TS(N) signals. Here the signal appears on the display and the maximum temperature can be set. In case of level excess the protective functions begin to operate.
This channel monitors the operational noises of the bearings. The SPM 40000 type (SPM Instruments Sweden) shock pulse transducers are near the bearing houses. The shock pulses generated in running bearing are transformed into electrical signals in the transducer. These signals are transmitted to the preamplifier by short coaxial cables. The NFP-02.04 preamplifiers whose sensitivity can be adjusted by front panel organ are complete measuring units with pre-programmed alarm levels. Its sensitivity can be set in the range of 28 to 75 dBsv. In our case d=30mm,that means that dBsv = 55 to 65 can be chosen. In alarm situation the current consumption of the preamplifier increases.
The NFI-07.6 type Sensor Interface unit supplies the preamplifiers with 24 V AC. It detects the change in the current consumption of the preamplifier. The bearing noise level control could be adjusted as low as 45 dBsv.
The selector discs are rotating in a vacuum. So the vacuum level has to be measured by this channel. The air friction of the discs was studied by varying the pressure in the vacuum housing and it was established that below 10 hPa (10 mbar) the power requirement is practically independent of the pressure. It is advisable to set the limit at this level although the pressure may decrease even below 1 hPa (1 mbar).
At emergency situation about 2 min. is needed to stop the rotor by increasing the pressure in housing to atmosphere.
The signal of the vacuum gauge reaches the NFI-07.06 Sensor Interface unit. The pressure value is displayed.
The NFI-07.16 type Sensor Interface unit receives the signals coming from the rotor tilt angle sensor of type ANDIMIK-I-04-960-0.
Square wave signal trains allow that 4 edges can be evaluated within one interval, which means for times resolution of the encoder (0.1o). By using the reference pulse appears once per revolution on the same (zero) position the unit is able to compute the absolute angular position calibrated each time the selector body is crossing the zero position.
That is the reason the automatic zero position searching can be achieved.
Also this unit controls the dc servomotor to turn the selector body into the wished position automatically and receives signals of the end-position switches.
The signals of the measuring channels are supervised by the limit value monitor system.
In the following the most important safety functions are listed:
In case of the safety functions came into action, the device will automatically be set to the STOP state and the LEDs on the right side of the displays will flash indicating the reason of the stopping.
There are several sensors mounted on the mechanism to provide electrical signals corresponding the state of the neutron velocity selector.
Because of the existence of the magnetic shaft coupler, it is necessary to measure the revolution speed of both the motor and selector rotor shaft.
The A06050M2 type magnetic rotation sensor gives signals of 10 sine waves per revolution with amplitudes that depend on the rotation speed. The sensor is formed from a stepping motor with permanent magnet rotor part. The stator involves two windings supplying signals with a phase shift of 90°.
The measurements of L05063R1 type vacuum probe are based on the Pirani principle.
The instrument provides heating voltage for the thin platinum filament placed into the space to be measured. The temperature and with it the resistance of the filament increase. The extent of the temperature increase depends on the heat conductivity of the vacuum space, and there is a direct correlation between the heat conductivity and the extent of the vacuum. In our application the temperature of the heating filament is kept constant (150°C) and the necessary heating power is measured. This feature is favorable as the influence of the temperature of the environment is decreased.
The Iset output current of the LM 334 type sensing element is proportional to absolute temperature in degrees Kelvin. Iset at any temperature can be calculated from: Iset = I0 (T/T0) where I0 is I set measured at T0 (K).
Calibration of the LM 334 is carried out by trim resistor Rset. The nominal value of Rset is 230 ohm. It must be trimmed to get the sensitivity of 1 µA/K. It means that at °20 C temperature the output current should be 293 µA ± 1 µA. A 33 ppm/C drift of Rset gives 1% slope error because the resistor will normally see about the same temperature variations as the LM 334H.
The SPM 40000 type of shock pulse transducer is mounted near to the bearing houses. It transforms the shock pulses generated in running bearing into electrical signals. These signals are forwarded to two preamplifiers of type NFP-02.04 of variable gain.
The motor assembly consists of the asynchronous squirrel cage motor, the magnetic rotation sensor and one half of magnetic shaft coupler.
The 2VZA 80B2B5 type asynchronous squirrel cage motor is designed for continuous operation with installation dimensions according to IEC 72.
The stator is made of aluminum profile as the bearing shields and the bearing covers are made of forged aluminum. The termination box is formed from fiber glass fastened plastic material. The protection of the motors corresponds to the class IP 44 according to the DIN 40050. This means a protection against an incidental contact of the live parts with a tool of larger than 1 mm and against the penetration of a water jet coming from any direction, but without pressure.
Prior to mounting the rotor and magnetic shaft coupler are dynamically balanced.
The most important electrical characteristics of the motor:
Voltage range: 3 x 0 to 220V
Frequency range: 1 to 120Hz
Power max.: 1.1k W
Rotation speed: 300 to 7000rpm
Ambient temperature: max. 40° C
Weight: 10 kg
The three ends of the stator windings are conducted to the connecting screws in terminal box. By applying connecting plates, the windings are connected into stator. In addition, there is also a separate earthing screw in the terminal box.
Because of the existence of the magnetic shaft coupler it is necessary to measure the revolution speed of both the motor and selector rotor shaft. The A06050M2 type magnetic revolution number sensor mounted to the shaft of driving motor gives signals of 10 sine waves per revolution with amplitudes that depend on the rotation speed.
The operation of rotor tilt angle sensor type ANDIMIK-I-04-960-0 is as follows:
The light of the infrared light sources pass through the taste plate and the code-carrier which move compared to the taste plate. The light is sensed by the phototransistors. Due to the turning away of the disc the phototransistors sense almost sinusoidal changes in the intensity of the light. In consequence the suitable location of the light sources and sensors and the adequate shaping of the taste plate the sinusoidal electric signals are shifted by 90° to each other. 90° phase shifted square pulse signal trains can convert into these signals to each other by using adequate amplification, comparation and signal shaping.It is obvious from the signal diagram that if we count only the raising edges then the number of the measuring steps is equal to that of the counts and of the total signal periods. If we consider the raising and falling edges , then the evaluation is two-fold. If we consider all the edges of both signal trains, then the evaluation is four-fold. The two signal trains shifted by 90° to each other, using a suitable logical circuit, allow the determination of the direction. It is also obvious from the incremental system that at switching on the present point should be restored once again and this is served by the reference pulse. With the shaft encoder this reference pulse appears once per revolution and its width is half of that of the main pulses. The signal diagram shows that each signal has its inverse one used in the noise elimination.
The NFA-06.05 type Selector controller has to be placed into the outside of the radiation shielding. The distance between the mechanism and controller is max. 5m. The delivered mechanism and the electronic A06050C1 and A06050C2 type cables provide for the electrical connection between the electronic. The system needs mains of nominal 220V/50-60Hz / 6A with protective ground. The A06050C4 type cable is for the connection the electronic unit to mains.
DO NOT USE THE INSTRUMENT IF THE MAINS IS NOT GROUNDED!
Set the range of the NFP-02.04 (SPM 32 PL) preamplifier to 75 dBsv. When the selector is running at 6000 rpm, change the sensitivity slowly until the error message appears on the display. Add 20 dBsv for alert or 30 dBsv for danger limit. If the alert limit is adjusted, the error message means that a bearing repair must be planned. In these situation add an extra 10 dBsw on the preamplifier. Make the bearing repair within the next 500 operation hours or at the appearance of the new error code. In the case of danger limit, the error code indicates the need of immediate bearing exchange.
After pushing START button when the selector is rotating first you must wait until the speed drops below 1200 rpm. Then the vacuum pump can be switched out. After switching-off the NFA-06.05 with the OFF (red) button you should wait until the rotation speed decreases to 0 rpm without switching-off the vacuum pump.
If you want to restart without switching-off the system than after pushing the START button you out by disconnecting the mains cable.
Before switch off the NFL-06.05 with the "OFF" (red) button, put the "STOP" state.
All controls and indicators are on the front panel except the mains switch (KA) of the analogue supply unit.
MAINS mains connector, by which the electronics is connected to the grounded mains of 220V;
SENSOR sensors, tilt angle control motor, fastening valves on the mechanism are supplied through this connector.
· the rotation speed sensors;
· the 2 preamplifiers of the bearing noise trip signals;
· temperature sensor in the bearing on the neutron side;
· temperature sensor in the bearing on the motor side;
· the vacuum sensor;
· rotor tilt angle sensor;
· tilt angle controlling motor;
· end- and clamping position sensors.
MOTOR asynchronous ac motor:
2 mains fuses (10A) of analogue power supply.
motor push-button and lamp.
motor push-button and lamp.
operating parameters of the neutron selector can be adjusted and displayed by using the controls and displays on the right side
of the front panel.
to dealing with the detailed operation instructions we should be familiar
with the location and role of the 2x4-digit display and of the 12
pushbuttons of the keyboard. They are the following.
The device has two basic operation states:
1. In STOP operation state the tilt angle between the rotor shaft and the neutron beam, the limit values of the safety system and the starting set point of the rotation speed controller can be adjusted.
2. In START state the set point of the rotation speed controller can be adjusted.
switching on, the device is automatically set to STOP state. Pushing the
START button may make a change between the two states. The LED on the
START button indicates the actual state. (When this lights up, the device
is in START operation state.)
switch from the STOP to the START state is possible only if:
the angle-adjusting mechanism reaches a fixed position (the grad
LED next to the lower LED display ceases to flash);
the pressure around the rotor is less than 10 or 1 hPa, according
to PAR5 (may be read off on the upper display);
the momentary temperature of the bearings is lower than the maximum
value given in PAR2 (to be
checked by button TEMPN/TEMPM).
START state to STOP state the device can be switched over at any time
the two basic operating states there are different modes of operation. The
LED’s in the buttons indicates these.
When switched on, the device is automatically set to this mode which is indicated by the LED in the PRESS/ANGLE button. The angles can be adjusted between ±3.9 ° by buttons ®, , and ¯.
The adjustment of a new tilt angle consists of three phases:
1. The pneumatic fixing is loosened,
2. The servomotor turns the selector body to the wanted angular position.
3. The selector is fixed by the pneumatic system.
The pneumatic fixation is
released only after the selector body has stopped completely. During the
above process of angle adjustment the grad LED's flashing warns the user
that the selector cannot be switched over to START state.
The pneumatic fixation is released only after the selector body has stopped completely. During the above process of angle adjustment the grad LED's flashing warns the user that the selector cannot be switched over to START state.
This tilt angle can be displayed by the pressing of PRESS/ANGLE button. The controller accepts a new tilt angle set value only after pressing the button ENT. In this mode the upper display indicate the momentary value of the internal pressure. (Momentary va1ue of the inerna1 pressure, the 1ower one the tilt angle.)
An error code of 21 is displayed if during the adjustment of the angle the fixation has not occurred, or the body of the selector is on end position.
A turning wheel can turn the selector body manually. The range of this vertical tilt angle is d = ± 10°. The actual value of d can be read from the scale of tilt angle meter.
The TEMPN/TEMPM button enters this mode. The lower display shows the momentary temperature of the bearing on the motor side and the upper ones that of the bearing on the selector side. The mode can be left by any button functioning in STOP state.
Enter by the ROTN/SETP button. The upper display shows the momentary rotation speed of the selector, the lower one the rotation speed set point. The wanted value is adjusted between 700 and 7000 by the "® " " and " ¯ " buttons. If the selected value is higher than 7000, this will be overwritten to be 7000. If the selected selected value is less than 700, this will be overwritten to be 700. The wrong adjustment is indicated by the rpm LED flashing.
controller accepts a new rotation speed set point only after pushing the
button ENT. The changing speed is equal to PARO (1 to 10 rpm/s,
default 10 rpm/s).
The actual values of the five safety parameters can be displayed by repeatedly pressing the PAR button. The index of the actually displayed parameter is shown by the 7-segment display in the PAR button.
The meaning and adjustable maximum values of the individual parameters are the following:
PAR1 - max. rotation speed : 7350rpm
PAR2 - max. temperature : 61 Co
- max. control deviation : ±
- max. power :
- max. pressure : 10 hPa
PAR6 - changing speed of set point : 1 to 10 rpm/s
The above listed values are the defaults. Customers are able only to decrease these limits.
The following safety functions are connected to the above:
The values of the PAR1-4 and PAR6 parameters are set by buttons " ® ", " and" ". The limit value of the pressure monitor can be set to three discrete values by button " ® ".
Upon pressing the ENT button, the selected values are written to the memory of the device.
Should any of the safety functions come into action, the device will automatically be set to the STOP state and the LED's on the right side of the displays will flash indicating the reason of the stopping. Then the device is automatically set to the mode of internal selector pressure indication and angle adjustment. The parameter adjustment modes can be left by repeatedly pushing the ENT button.
A switch from the STOP to the START state is possible only if
When switched over to the START state, the device is automatically set to this mode, which is indicated by the LED in the ROTN/SETP button. Then the upper display shows the rotation speed of selector rotator and the lower one the rotation speed set point. The new value is adjusted by buttons " ® ", " " and " ¯ " as was described under the modes of the STOP state.
When pushing the ENT button, the motor takes the new rotation speed according to the set point and the change over to another mode of the START state is enabled again.
The rotation speed set point can repeatedly be changed by pushing the ROTN /SET P button again.
The following modes are only used to indicate the operating characteristics in the START state:
1. Selector rotation speed and power: ROTN/POWER
2. Selector's and motor's speed of rotation: ROTN /ROTM
3. Selector rotation speed and control deviation: ROTN /DEV
4. Bearing temperature: TEMPN/TEMPM
5. Pressure and angular position: PRESS/ANGLE
These modes are selected in START state without pushing the ENT button. Selection of the values by buttons "®", " "and " ¯ " . Button " ® " is used for changing the digits from left to right and buttons " " and " ¯ " for varying their values upwards and downwards, respectively.
The device reacts to the appropriate buttons only, so no damage can be caused by erroneous operation. In both basic states, erroneous pushing of any of the buttons causes all digits to display the "-" character. Upon pushing the proper button, these characters disappear.
A battery feeds the memory of the device, so the selected set point, angular position or parameter values do not get lost when the device is switched off.
The device is equipped with a standard RS-232C interface. Setting of the asynchronous communication interface: 1 start bit, 8 data bits (ASCII), 2 stop bits, parity even, 9600 baud.
The RS-232C line is activated when the device is switched on. The serial line accommodates the performance of four functions, which are initiated by the HOST machine.
The HOST machine has to send a "P" (Parameters) ASCII character indicating the request for parameters. Upon this the device sends out all measured parameters through the serial line in the following order:
RPAP Rotation stop, angle adjustment stop.
RPAT Rotation stop, angle adjustment start.
RTAP Rotation start, angle adjustment stop.
Rotation speed: rpm
Pressure: [ (1.char.,2.char./10) *10(3.CHAR)(4.CHAR.) ] hPa
Angular position: °.
Each parameter is four ASCII characters long. A „space” (SP) character separates the parameters from each other. The message is terminated by a CR/LF character pair.
The HOST machine has to send a "C" (Control) character. Then the device waits for a message consisting of four ASCII characters and terminated by a CR/LF.
These four characters determine the new value of the rotation speed. If this number exceeds the maximum value written at the set point adjustment, it will be modified to the 7000 rpm value and this will be considered as the set point.
The HOST machine sends an "H" (Halt) ASCII character to put the device to STOP state and angle setting mode.
The HOST machine sends an "A" (Angle) ASCII character followed by a message consisting of four ASCII characters which is terminated by a CR/LF. The first is the sign, the third is the decimal point character. This setting is only accepted by the control unit if it is in STOP state and if the value is between - 3.9 and + 39.
An „S” (Start) ASCII character does it. This command is accepted if the above described conditions are fulfilled. If the characters are letters, the control unit sends and accepts uppercase characters only.
4.6.6 Error Messages
In the event of an erroneous command from the HOST machine, the control unit sends the following message:
The number following the word "error" indicates the cause of the error. The meaning of the values is the following:
01: Other character (s) as "P", "S", "H", "C" and "A" has been sent or the operand from following "C" and "A" command is differ from that prescribed previously.
02: It is sent following the character "A" if the program is in
· START state.
· PAR1 to PAR5 state.
· STOP state the rotation speed reference signal is under adjustment.
: It is sent after "S", "H" and "C" commands
it the rotor tilt angle is under
04: It is sent after the character "H" if the program is in the STOP state.
05: It is sent after the character "S" if
the conditions to start (vacuum, bearing temperature, standing rotor) hav not fulfilled.
the controller is in START or PAR1 to PAR5 state.
in STOP state the rotation speed reference signal is under adjustment.
06: It is sent after the characters "P" or "C" if the controller is in PAR1 to PAR5 state or the rotation speed reference signal is under adjustment.
Should an error occur during the operation of the controller, to send an error message as follows:
The meaning of the error codes is the following:
10: Selector rotation speed exceeded the permitted maximum;
11: Motor rotation speed exceeded the permitted maximum;
12: Bearing temperature on the selector side exceeded the prescribed maximum;
13: Bearing temperature on the motor side exceeded the prescribed maximum;
14: Control deviation exceeded the prescribed maximum;
15: Motor performance exceeded the prescribed maximum;
16: Internal selector pressure is higher than the prescribed maximum;
17: Vibration of the selector side bearing is too high;
18: Vibration of the motor side bearing is too high;
19: The difference between the selector and motor rotation speeds exceeded 300 rpm.
20: Fixation of the angle adjustment has been released.
21: During the adjustment of the angle the fixation has not occurred.