SMARTSCAN INFORMATION

Transcription

1 SMARTSCAN INFORMATION SS SLC NOV05 SLC2 and SLC4 SAFETY INDUCTIVE LOOP CONTROLLERS INSTALLATION GUIDE Smartscan Ltd, Pywell Road, CORBY, NN17 5XJ, UK, Tel: +44 (0) , Fax: +44 (0) , ISSUE 1

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3 1 Smartscan Inductive Loop Controllers for Machine Safety Applications Loop controllers SLC2 and SLC4. Smartscan inductive loop controllers are used in a number of machine safety applications wherever the presence of fork lift trucks or other industrial vehicles needs to be detected, for example, when entering safe guarded access ways or, at pallet conveyors for loading and unloading. The output signals from the loop controllers are normally used for muting Smartscan safety light curtains. Application Overview Fig. 1 As a loaded pallet moves along the conveyor away from the dangerous machinery it enters the load / unload area at which point the conveyor stops. This load/unload area is safe guarded by a Smartscan light curtain which is positioned to detect personnel accessing the potentially dangerous machinery. As the forklift truck enters the area it passes over the underfloor mounted dual inductive loops which detect it s presence and provides output signals via the inductive loop controller to mute the light curtain. After inserting or unloading the loaded pallet, from the conveyor the forklift truck moves out of the area and therefore off the inductive loops. At this point the muting signals are removed and the light curtain becomes fully active again, thus providing fully automatic control of the machine and safety system. Smartscan loop controllers directly interface with all Series 8000 and safety light curtains.

4 2 Functional description of loop controllers SLC4 and SLC2 Smartscan loop controller SLC4 uses two loop evaluation units (LD21) in conjunction with a Smartscan 8000 or 8000 Plus Series safety light curtain to provide a control system integrity up to Category 4, as defined in European Standard EN Smartscan loop controller SLC2 uses one evaluation unit (LD40) that monitors two inductive loops from a single unit. When used in conjunction with a Smartscan 8000 or 8000 Plus Series safety light curtain they provide a control system integrity up to Category 2, as defined in European Standard EN The principle of operation of the evaluation units is based on a change in the inductance within the loop that is created by the metallic components of passing vehicles. The changes are picked up and evaluated by a microprocessor within the units. Benefits for the customer Ease of use automatic calibration of the system when the operating voltage is applied. Reliability compensation for temperature fluctuation. Sensitivity setting 3 position switch (high, medium, low). Simple fault detection with light emitting diode to display possible malfunctions. Simple reset function forces a re calibration by changing the sensitivity. There is no need to shut off the voltage. Waterproof Enclosure Smartscan loop controllers are mounted in an enclosure providing a protection rating of IP65 Status Diagnostics LED indicators for power, system reset (controller outputs on ), calibration complete, mute and inductive loop(s) outputs active.

5 3 Loop Evaluation Units LD21 and LD40 Loop evaluation units have the following outstanding features: Automatic adjustment Automatic temperature compensation Large inductive working area ( µH) Micro processor control system Three sensitivity levels Two frequency settings Technical description The inductive loop and it s associated capacitance is linked to the evaluation unit to form a LC oscillator. The frequency of the resonance circuit is determined by the capacitor and the magnitude of the loop inductance. The capacity of the capacitor and thus the resonance frequency can be modified using an internal switch. This prevents interference between two adjacent inductive loops or detectors. General Rule: The higher the inductance, the lower the resonant frequency. If a current is present in the loop, an alternative magnetic field is generated around it. The magnetic field lines close to form loops. When a vehicle moves onto the inductive loop, the alternating field of the loop induces currents in the metallic parts of the vehicle (chassis, axles). These currents generate a magnetic field which opposes the loop field. This results in a change in the loop inductance and thus the frequency. The loop detector detects this change in frequency. Such a change, beyond a pre determined threshold, activates the loop controller s output relay contacts.

6 4 The switching threshold can be adjusted using the sensitivity switch (High Medium Low). <High> means the switching threshold is low. <Low> means the threshold is high. The sensitivity should always be adapted to the respective area of application. Slow frequency changes (e.g. due to temperature variations) do not cause the output relay to switch. Technical data SLC2 & SLC4 Operating voltages 24V ACDC ± 10% Power consumption < 6 VA Safety Relay output 110 V / 2 A, N/O contacts Duty cycle 100% Frequency range 20 khz to170 khz Loop inductance (incl. connection wiring) Ideal: 80µH to 300 µh Max: 40 µh to 1000 µh Loop connection wiring Max. 200 m Twisted at least 20 times/m Operating temperature 20ºC to +55 ºC Storage temperature 40ºC to +70 ºC Temp. compensation Max. 50 ºC/h (automatic) Max hold interval in case of power 3 Seconds. loss Protection class IP65 Interference protection In acc. With EN /EN

7 5 Installation and set up of loop controllers Ensure the loop evaluation units are protected from moisture. Power up the loop controller: 1. At start up the underfloor loops must not be obstructed by a vehicle etc. (they must be in a non activated condition). At this point the evaluation units automatically calibrate. The calibration takes approximately 3 seconds at which point the red led on each unit is continuously lit. 2. When calibration is complete correct functioning can be checked by activating the loop(s) with the intended object e.g. fork lift truck. The units output relay must energise when the loop is activated and de energised when the loop is clear. 3. If the loop evaluation is not activated by the truck the sensitivity switch must be set one step higher. Sensitivity The loop response sensitivity is set by using the three position switch(s) on the front of each evaluation unit. LOW corresponds to the lowest sensitivity where and HIGH to the highest sensitivity. After setting re calibration takes place automatically. Fig. 2

8 6 Frequency The frequency of the evaluation unit type LD21 can be changed to avoid interference between two adjacent evaluation units. One of two frequency levels can be selected using the internal DIP switch. To do this, switch off the power and remove the outer case. Fig. 3 Functions of the loop evaluation unit output relays. Type LD21 The output relay from each evaluation unit energises when each loop is activated and is released when the loops return to a non activated condition. A malfunction causes the output relay to drop out automatically. Type LD40 The corresponding output relay in the evaluation unit energises when loop 1 or 2 is activated and releases when the loops return to a non activated condition. A malfunction causes both output relays to release automatically. Troubleshooting At power up the red led does not light up and no calibration takes place. Possible cause. Supply voltage not OK or, faulty unit. Red led flashes a number of times or continuously. Flashes 2 times = loop too large. Measure inductance micro Henrys Flashes 4 times = loop too small. Measure inductance micro Henrys Flashes 6 times = Loop interruption. Loop fault, loose ground under loop. The loop must not move when a truck passes over. Flashes continuously = DIP switch error. Remove cover and check settings

9 7 Inductive loops Loop geometry The loop geometry must be adapted to the respective application. Sensitivity is optimal if the loop is not bigger than the object to be detected. For installation reasons, the loops generally have a rectangular design. This geometry is suited for detecting forklift trucks and AGV s etc. Fig. 4 Number of loop windings The number of windings depends on the circumference of the loop. The smaller the loop, the more windings are required. Loop circumference Number of windings Under 3m Contact us 3 6 m 5 windings 6 10 m 4 windings m 3 windings > 25 m 2 windings

10 8 Installing the loop After determining the loop geometry, a groove (5 8 mm wide, 30 50mm deep) must be cut in the floor for installing the loop. We recommend cutting an inclined groove (45º angle) at the corners of the loop. Routing the loop wire along this incline will protect it from excessive wear at the corners. The groove must then be cleaned avoiding any kind of moisture. Run the loop wire as tight as possible along the very bottom of the groove. You can use commercial copper strand (flexible, insulated, 1.5mm²) as loop wire. Prior to sealing up the groove, the loop inductance should be checked using a measuring device and modified as required (optimum value µh). Then run a nylon cord along the loop and seal up the groove. Suitable sealing compounds are, for example, bitumen or artificial resin. Fig. 5 Once the sealing compound has set, an earth leakage measurement must be carried out. The loop detector can then be connected to the power supply. CAUTION! When sealing up the groove, ensure that the temperature of the sealing compound (e.g. hot bitumen) does not exceed the maximum admissible temperature of the loop insulation, as this might cause an earth fault. Use a heatresistant insulated wire for such cases.

11 9 Installation Normally, for machine safety applications two underfloor inductive loops are installed as in Fig. 6 Fig. 6 Select the shortest loop connection wiring possible and route it separately from any power lines. The parallel distance to power lines should be at least 10 cm. A distance must also be kept between the loop connection wirings of different detectors. Both connection wires must be twisted at least 20 times per meter, all the way from the control cabinet to the detector. Connection wires must not be routed through the groove of an adjacent loop and must be protected from mechanical damage. If the loop is to be installed in soft ground, ensure that vehicles moving onto the loop and the connection wiring will not cause them to move. Every single winding and the loop itself must be in an absolutely fixed position. Movements of the loop or individual windings can cause false tripping. The distance to adjacent loops or movable metallic objects (e.g. sliding gates) must be at least 1m. Fig. 7

12 10 A maximum distance should be kept from reinforced concrete. This distance must be at least 40mm. There must be no movable objects (e.g. gratings, gully covers) in the loop detection area.

13 11 APPENDIX 1 Application Examples Figures 8 and 9 show an application where forklift trucks are used to place and remove palletised loads from the infeed or outfeed conveyor of a potentially dangerous machine. The application shows light curtains operating in conjunction with a control system and strategically positioned under floor inductive loops, that enable continuous but safe operation of the machinery even during periods when a forklift truck is loading or unloading the pallet loads in close proximity. Fig. 8 Figure 8 shows a hazardous machine surrounded by fixed fences. The open area across the conveyor is safeguarded with two light curtains that operate in a specific sequence. When light curtain 2 is active, or ON then light curtain 1 is muted e.g. the electrical outputs from light curtain 1 do not respond to an interruption of its detection field. When light curtain 2 is muted then light curtain 1 is automatically switched ON. Light curtain 2 is automatically muted with signals derived from the under floor inductive loops. These signals mute light curtain 2 when the metal mass of the forklift truck is positioned above the loops. When the forklift truck moves away from the loops the muting signals are removed and light curtain 2 once again becomes active at the same time deactivating or muting light curtain 1. It can be seen that there is always one of the light curtains in an active, ON condition, thus preventing personnel access to the machinery at all times but, still allowing continuous machine operation.

14 12 Figure 9 shows another packaging machine application using control functionality similar to the system previously described. However, in this case two forklift truck load / unload stations are installed, each safeguarded with a light curtain and an inductive loop control muting system. Figure 9 Figure 10 shows a rather more complex safety control system where the machinery is separated into four specific safe zones, however the system uses much of the safety control functionality for the applications previously described in this section. Figure 10

15 13 APPENDIX 2.1 Smartscan 8000 Series SLC4 Inductive Loop Control System R E C E I V E R 8000 Series A Cable T R A N S M I T T E R Rocker switch mounted on controller enclosure Guard Reset Loop Reset Inductive loop controller ( ) B Cable Mute 1 Note: Link mute enable to 24V DC if not used. Mute 2 INDUCTIVE LOOPS TO MACHINE CONTROL

16 14 SLC4 APPENDIX 2.2 1TB Cable B colour code Destination 1 Brown/white L+ 24V dc 2 Orange/white L 0V dc 3 Grey Mute enable 4 White Status 5 Green Status 6 Red OSSD1 7 Black OSSD1 8 Blue OSSD2 9 Brown OSSD2 10 Red/white Activate / Reset 11 Yellow EDM 12 Black/white Mode (L 0V dc) 13 Violet Mute output (L 0V dc) 3TB Cable M1 colour code Destination 1 Black Mute 1 connector 2 Blue Mute 1 connector 4TB Cable M2 colour code Destination 1 Black Mute 2 connector 2 Blue Mute 2 connector 5TB Cable colour code Destination 1 N/A Loop1 2 N/A Loop2 3 N/A Loop2 4 N/A Loop2 2TB Cable colour code Destination 1 N/A L+ 24V dc 2 N/A L 0V dc 3 N/A Ground 4 N/A Safe out 1 5 N/A Safe out 2 6 N/A Safe out 2 7 N/A Safe out 2 8 N/A Mute enable Note: Link 2TB1 to 2TB8 if MUTE ENABLE is not used.

17 15 SLC4 APPENDIX 2.3 Calibration Ok Output On High Medium Low Red Blue Green Sensitivity Switch Calibration Ok Output On High Medium Low Status Indication Power A red LED indicator is illuminated to show that the controller is receiving power. Mute A blue LED indicator illuminates when the inductive loops are obstructed by a forklift truck and the light curtain output relays are in a muted condition. Clear A green LED illuminates when the inductive loops are clear of obstruction by a forklift truck and the safety system is fully active again. Evaluation Units Calibration OK A steady red LED indicator shows that the inductive loop calibration is complete. Output On A green LED indicator comes on to show that the evaluation unit output relay is active (inductive loop covered).

18 16 APPENDIX 3.1 Smartscan 8000 Series SLC2 Inductive Loop Control System R E C E I V E R 8000 Series A Cable T R A N S M I T T E R Rocker switch mounted on controller enclosure Guard Reset Loop Reset Inductive loop controller ( ) B Cable Mute 1 Note: Link mute enable to 24V DC if not used. Mute 2 INDUCTIVE LOOPS TO MACHINE CONTROL

19 17 SLC2 APPENDIX 3.2 1TB Cable B colour code Destination 1 Brown/white L+ 24V dc 2 Orange/white L 0V dc 3 Grey Mute enable 4 White Status 5 Green Status 6 Red OSSD1 7 Black OSSD1 8 Blue OSSD2 9 Brown OSSD2 10 Red/white Activate / Reset 11 Yellow EDM 12 Black/white Mode (L 0V dc) 13 Violet Mute output (L 0V dc) 3TB Cable M1 colour code Destination 1 Black Mute 1 connector 2 Blue Mute 1 connector 4TB Cable M2 colour code Destination 1 Black Mute 2 connector 2 Blue Mute 2 connector 5TB Cable colour code Destination 1 N/A Loop1 2 N/A Loop2 3 N/A Loop2 4 N/A Loop2 2TB Cable colour code Destination 1 N/A L+ 24V dc 2 N/A L 0V dc 3 N/A Ground 4 N/A Safe out 1 5 N/A Safe out 2 6 N/A Safe out 2 7 N/A Safe out 2 8 N/A Mute enable Note: Link 2TB1 to 2TB8 if MUTE ENABLE is not used.

20 18 SLC2 APPENDIX 3.3 LOOP 1 Calibration Ok Output On High Medium Low Calibration Ok Output Red Blue Green High Medium Low Sensitivity Switch Status Indication Power A red LED indicator is illuminated to show that the controller is receiving power. Mute A blue LED indicator illuminates when the inductive loops are obstructed by a forklift truck and the light curtain output relays are in a muted condition. Clear A green LED illuminates when the inductive loops are clear of obstruction by a forklift truck and the safety system is fully active again. Evaluation Units Calibration OK A steady red LED indicator shows that the inductive loop calibration is complete. Output On A green LED indicator comes on to show that the evaluation unit output relay is active (inductive loop covered).