Part 11 Metal Detector Manual

MA3000

ERIEZ METALARM PAGE 1

E R I E Z M E T A L A R M

MA3000 SERIES M E T A L D E T E C T O R

Description of Installation and Operation

DOCUMENT No: IOM-MA-3000 REVISION: A

ERIEZ MAGNETICS EUROPE LIMITED

BEDWAS HOUSE INDUSTRIAL ESTATE BEDWAS CAERPHILLY CF83 8YG UNITED KINGDOM TEL. +44 (0) 2920 868501 FAX. +44 (0) 2920 851314

SERIAL NUMBER: 81447

CHECKED BY:

DATE:

MA3000


Table of Contents 1.0 INTRODUCTION 2.0 INSTALLATION 2.1 Control Unit Mounting 2.2 Search coil Mounting 2.2.1 Underbelt TR Coil (Flat Pack) 2.2.2 TR10 Coil 2.2.3 Bridge Coil 2.2.4 U section belt conveyors or vibrator conveyors 2.2.5 Plate Coil

3.0 ELECTRICAL CONNECTIONS 3.1 Power Supply 3.2 Sensor Coil Connections 3.3 Control Relay Contacts 3.4 Fuse 4.0 OPERATING INSTRUCTIONS 4.1 Indicator Lights 4.2 Sensitivity Adjustment 4.3 Signal Level Indicator 4.4 Electronic Board Mounted Switches 5.0 ELECTRONIC CIRCUIT BOARD REPLACEMENT 6.0 WIRING TO THE CONVEYOR MOTOR CONTACTOR 7.0 AUXILIARY RELAY 7.1 Auxiliary Relay Wiring 8.0 EARTHING OF ASSOCIATED EQUIPMENT WHEN FREQUENCY INVERTER SPEED CONTROLS ARE

BEING USED 9.0 SUGGESTIONS FOR TROUBLE SHOOTING ENVIRONMENTAL INTERFERENCE 9.1 Movement of Metal 9.2 Intermittent Loops of metal surrounding the sensor 9.3 Excessive line voltage fluctuations

9.4 Proximity of severe RF radiation source 10.0 PARTS LIST 11.0 TECHNICAL DATA

MA3000


METALARM 3000 CE 1.0 INTRODUCTION The METALARM (MA) 3000 Metal Detector, consists of a control unit, one or more sensor coils dependent upon the application and optional accessories such as the sack dropper. The optional QUARRYMASTER version of the control unit is constructed from stainless steel and is fitted with an anti condensation heater & thermostat for frost protection. The thermostat is normally set to +5°C. These instructions are concerned with the installation and operation of the control unit, sensor coils and accessories.

Figure 1

MA3000


2.0 INSTALLATION 2.1 Control Unit Mounting

The MA3000 control unit is supplied with HDPE (high density polyurethane) mounting brackets for wall mounting. Dimensions are shown in the diagram, Figure 1.

Ideally the control unit should be mounted within 3-5 metres of the sensor coil unit and no more than 20 metres.

The MA3000 control unit will normally be mounted by means of four M8 or 5/16 inch bolts utilizing the four mounting holes.

Adequate clearance must be allowed below the control unit enclosure to allow for cable entry and exit.

On no account must the HDPE mounting brackets be replaced, as these are provided to electrically isolate the control unit from the metal conveyor framework. Similarly no metal work should be in contact with the metal control unit case after mounting on the conveyor.

Failure to comply with the above mounting procedures will invalidate the 'CE' certificate covering the EMC regulations.

2.2 Search Coil Mounting

The following instructions give details of how to install the various types of standard search coils supplied as part of the Metalarm Metal Detector.

2.2.1 Underbelt TR (Flatpack) Coil - Idler Conveyors (figure 2)

A) Locate a suitable position in the conveyor mid way between two idler sets where: 1. There will not be a return idler or cross piece beneath the search coil.

2. There is no join in the conveyor frame

3. Metal when detected can easily be removed from the conveyor belt

4. There is no moving metal in the vicinity

5. Where any metal base plate present can be removed or replaced by non metallic material.

6. Where any metal over-belt covers can be removed or replaced

B) Place the search coil on the conveyor frame at the chosen position. There should be at least a

25mm (1 inch) gap between the underneath of the (fully loaded) conveyor belt and the top of the search coil. If not cut out notches in the bottom of the search coil at all four corners so as to lower the search coil within the conveyor frame.

C) Brackets to hold the search coil to the conveyor frame (not supplied) should be fitted to the coil to secure it to the conveyor stringers.

D) The search coil should then be bolted to the conveyor frame so that the coil socket is on the opposite side of the conveyor frame to any heavy duty cables.

E) The idlers either side of the search coil should be checked to see that all nuts and bolts have been tightened down. Ideally the idler frames should also be spot welded once at each of the four corners to the conveyor frame.

MA3000


The cable to connect the search coil to the control unit should then be plugged into the underneath of the search coil and run back to the control unit. The cable should be tied down so it does not get damaged.

Figure 2 2.2.2 TR10 Type Search Coil – Idler Conveyors (figure 2A)

Follow the instructions as listed in section 2.2.1 points A-E for the coil location & installation.

This type of coil configuration is designed for transmit/receive mode operation only and both coils are connected directly to the control unit. See section 3.2 (sensor coil connections) and figure 2A below. Remember in both cases to make sure the cables are tied to the conveyor frame to prevent them being damaged.

Figure 2A

CO-AX CABLE TO METALARM CONTROL UNIT

CONVEYOR STRINGER

SENSOR COIL PLATES

SIDE SUPPORT PLATES

SMALL ANGLE BRACKETS (NOT SUPPLIED)


CONVEYOR STRINGER

SIDE SUPPORT PLATES

TRANSMITTER COIL

RECEIVER COIL

CENTRE SUPPORT PLATE

MA3000


2.2.3 Bridge Type Search Coil - Idler Conveyors (figure 2B) A) Locate a suitable position in the conveyor mid way between two idler sets where:

1. There will not be a return idler or cross piece beneath the search coil.

2. There is not a join in the conveyor frame

3. Metal when detected can easily be removed from the conveyor belt

4. There is no moving metal in the vicinity

5. Where any metal base plate present can be removed or replaced by non metallic material.

6. Where any metal over-belt covers can be removed or replaced.

B) Assemble the lower coil on the side supports & place on the conveyor frame at the chosen position. There should be at least a 25mm (1 inch) gap between the underneath of the (fully loaded) conveyor belt and the top of the search coil. If not cut out notches in the bottom of the search coil at all four corners so as to lower the search coil within the conveyor frame.

C) Brackets to hold the search coil to the conveyor frame (not supplied) should be fitted to the coil to secure it to the conveyor stringers.

D) The search coil should be mounted on the conveyor frame so that the coil socket is on the opposite side of the conveyor frame to any heavy duty cables.

E) Fit top search coil section and bolt down

F) The idlers either side of the search coil should be checked to see that all nuts and bolts have been tightened down. Ideally the idler frames should also be spot welded once at each of the four corners to the conveyor frame.

In the case of series connection, connect the lower coil using the short length of cable provided using the unmarked socket on the top coil. The cable to connect the search coil to the control unit should then be plugged into the socket marked ‘CU’ on the top search coil and run back to the control unit. See 3.2 In the case of transmit/receive mode operation; both coils are connected direct to the control unit. See 3.2. Remember, in both cases make sure the cables are tied to the conveyor frame to prevent them being damaged.

Figure 2B


CONVEYOR STRINGER

SIDE SUPPORT PLATES

TRANSMITTER COIL

RECEIVER COIL

MA3000


2.2.4 “U” Section belt conveyors or vibrator conveyors - Search coils (figure 3/4) A) Locate a suitable position in the conveyor where there is going to be no metal within 500mm of

the underneath of the search coil when it is mounted onto the conveyor. Simultaneously there is no moving metal in close proximity to the search coil. In the case of vibrator conveyor the coil is usually located midway between two of the vertical supports.

B) To install a trough coil, it is necessary to cut out a length of the base and part of the side walls of the conveyor. The dimensions of the required cut out can be found by measuring the recessed area of the search coil.

Figure 3 C) Draw a line 25mm from the edge of the cut out. Along this line drill M8 holes at 100mm (4 inches)

spacing or longer depending upon the weight and width of the search coil. Countersink the holes from inside the conveyor.

D) Locate the search coil into the cut out and clamp into position. Then using the trough as a template spot mark through the holes from the inside of the trough directly onto the coil.

E) Fix the search coil into position using countersunk M8 bolts x 40mm long, shakeproof washers, and nuts.

DRILL MOUNTING HOLES ALONG THIS PATH

COUNTERSINK FROM INNER SURFACES OF TROUGH

REMOVE SECTION FROM TROUGH

SECTION VIEW

SENSOR COIL

RECESSED AREA

CUT OUT LENGTH

CUT OUT HEIGHT

MA3000


F) The cable to connect the search coil to the control unit should then be plugged into the underneath of the search coil and run back to the control unit. The cable should be tied down so it does not get damaged.

Figure 4

UNDERSIDE VIEW

CO-AX CABLE TO METALARM CONTROL UNIT

M8 FIXINGS

MA3000


2.2.5 Plate Coil (figure 5) Plate coils can either be mounted beneath a pre-prepared metal free section such as wood or fiberglass, or providing the plate coil is an SF or SFC type directly onto the base of a metal sided conveyor.

In the latter case if the base of the conveyor is metal this must be removed for the length of the coil plus 3mm.

The search coil can be drilled into or through in any of the crossed areas shown below as long as it is a minimum of 25mm away from the coil windings.

Figure 5

SECTION VIEW

SENSOR COIL

CONVEYOR STRINGER

CONVEYOR BELT

FRONT VIEW

SENSOR COIL

DRILL

COIL WINDINGS

MA3000


3.0 ELECTRICAL CONNECTIONS - (See Figure 6.) The standard electrical connections are for power supply connections and for sensor coil connections. Other cables may be added as necessary for control and monitoring functions. Please note where armoured cables are being used, the armouring must be cut back at the gland plate of the control unit such that it does not touch the Metal Detector Control Unit, as this will compromise the electrical isolation of the Control Unit. This also applies to electrical trunking.

Figure 6 3.1 Power Supply The mains connection is made via the terminal block TB1 using 'E' for earth/ground connection, either of the 'L' terminals for live 1/positive connection and either of the 'N' terminals for live 2/neutral connection.

The spare 'L', ‘N’ and 'E' terminals can be used for driving external controls or the bag dropper accessory for example.

The Voltage Selector Switch should be set to 230VAC or 115VAC as required. This is located just above the connector TB1.

OPTIONAL: If the system has been requested to operate from a DC voltage, the input voltage must be within the range 18-30VDC. The input supply should be applied to the DIN rail terminal block mounted in the bottom of the control unit at the terminals listed below. 2 – NEGATIVE SUPPLY (0V – GREEN/YELLOW) 5 – POSITIVE SUPPLY (FUSED TERMINAL) NOTE The DIN rail terminals are not fitted in the standard mains (AC) powered units.

DIN RAIL TERMINAL BLOCK

(+)

(-)

LINE LOAD

2 5

4

31

DC

PSU INPUT

E E N L N L N/C C N/O N/C C N/O N/C C N/O N/C C N/O

OPTIONAL FAULT RELAY CONNECTION

DETECT RELAY

C C

230

1 2 3 4 5 6 TB1

1 2 3 4 5 6 7 8 9 TB3

1 2 3 4 TB4

POW

ER LIGH

T

RESET SWITC

H

DETEC

T LIGH

T

SENSOR COILS

MAINS POWER

AUXILIARY TERMINAL

1 2 3 4 5 6 7 8 9 10 11 12

TB2

EXT FAULT IN

PUT (+5VD

C)

1 2

SW4 POSITION 1: SINGLE COIL CONNECTION (TX) 2: SECOND COIL CONNECTION (RX)

MA3000


3.2 Sensor Coil Connections The sensor coil connection is made via the right hand 4 way terminal block TB4. When only one coil is used, or a Bridge coil is being used with coils in series, connect to terminals 3 & 4.

The inner conductor is connected to terminal 'C' and the outer braiding to terminal

For applications where two coil windings are being used and there are two coil cables, i.e. separate transmitter and receiver coils; the search coil with the coil socket marked ‘RX’ should be connected to TB4 1 and 2 and the search coil with coil socket marked ‘TX’ should be connected to TB4 3 and 4.

Note: Switch 4 should be moved to position 2, when in transmitter/receiver mode (TX/RX).

3.3 Control Relay Contacts Connection to the output contacts of the control relay are made to terminal block (TB2) as indicated in drawing Figure 6. Four sets of SPDT relay contacts are provided.

In the instance of the optional FAULT relay being fitted, then terminals 10, 11 & 12 of TB2 are used for this signal. This leaves three sets of SPDT relay contacts for the DETECT signal on TB2 (terminals 1-9). Note that the FAULT relay operates in a ‘fail-safe’ mode – so when power is applied to the control unit, it will change state.

The contacts are rated for 5 amps resistive, for either low voltage DC application or for a maximum of 250V ac application.

3.4 Fuse Please note there is only one fuse on this Control Unit, located on the front panel and rated at 500mA (230VAC) or 1A (115VAC) A/S. 4.0 OPERATING INSTRUCTIONS - (See Figure 7.)

Figure 7

Switch on the line power and the 'ON' lamp on the case door illuminates.

The red 'FAULT' light will be on if the sensor coil is not connected. When the sensor is properly connected the light will extinguish.

E E N N L L

MA3000


Note: The illuminated fault light will also cause the 'Detect' lamp to be on.

Rotate the SET ZERO control fully clockwise. If the right hand light illuminates, rotate the Set Zero control anti-clockwise until this light extinguishes and the green light illuminates.

This adjustment compensates or zeros out any near by metal in the sensor coil detect area. If this light cannot be illuminated there may be too much metal near the sensor coil. This can be confirmed by positioning the sensor coil away from all surrounding metal and repeating the test.

After these adjustments, the detector may have operated illuminating the 'Detect' light and the 'Reset' lamp on the detector door. Pressing the 'Reset' lamp button will extinguish both lights.

The ‘Relay’ switch controls the relay function. In the OFF position only the 'Detect light and door 'Reset' lamp operate when metal is present in the sensing area.

In the ON position, the 4 pole DPDT relay, the 'Detect' light and the door 'Reset' lamp operate when metal is present in the sensing area.

In the LATCH position, the relay and above indicators operate but after the metal is removed, the relay and the indicators remain on until either the door 'Reset' button is pressed or the 'Relay' switch is turned to the ON or OFF position.

The 'Sensitivity' control is a gain adjustment control to adjust for the detection of the desired size of material or to allow for smaller pieces of material to be ignored.

4.1 Indicator Lights

SET ZERO

When the Metalarm is operating and correctly set, the green light of these three lights is the only one illuminated.

If a piece of metal passing across the Sense coil is large enough it will cause the green light to go out and the right hand red light to come on while the metal is within the detect range of the Sense coil.

DETECT

This red light illuminates whenever metal is within the detect range of the Metalarm.

COIL FAULT

This red light illuminates if the sensor is either open circuit, not connected or short circuited.

This light also causes the Detect light to illuminate to prevent operation of the Metalarm until the coil fault is rectified.

Normally, the Metalarm control unit should not require any major re-adjustments after performing the adjustments during installation. After switching the control unit on, the green 'Set Zero' light should illuminate immediately without the need to turn the 'Set Zero' control. Proper operation may be verified by depressing the 'Test' button, which is mounted on the electronic circuit board beneath the front panel.

Certain extremely large objects may produce an overload signal causing the unit to indicate continuously even after the object has passed clear of the sensor coil. Depress the 'Reset' button to cancel the indication.

NOTE:

Although the control unit will adequately zero out stationary masses of background metal, it will respond to moving metal near the sensor coil. When mounting the sensor coil, consideration should not be limited to only large objects such as fork lift trucks, but should be extended to smaller objects such as maintenance workers carrying metal tools and equipment in the vicinity.

Although the metal detector system is suppressed against both airborne and power supply interference, some false alarms may nevertheless occur occasionally. Such triggering is usually due to transient effects, which are both infrequent and unpredictable.

Metallic framework encircling the search coil can act as a "shorted turn". It may be necessary to insert insulating sections to prevent comparatively small masses of metal generating inordinately large background signals.

MA3000


4.2 Sensitivity Adjustment

The 'Sensitivity' controls permit sensitivity adjustments for detecting or rejecting the desired size of objects. Rotate the 'Sensitivity' control clockwise to increase the Metalarm sensitivity or counter-clockwise to decrease the sensitivity.

A coarse sensitivity adjustment (VR1) may be performed by means of the sensitivity adjustment control on the control unit printed circuit board (see figure 8). Extreme care must be used in performing the coarse sensitivity adjustment. Consult the factory prior to making any coarse sensitivity adjustments.

NOTE:

Take particular care, as with the mains supply connected parts of the printed circuit board will be carrying high voltages. Therefore DO NOT touch anything other than the coarse sensitivity control you are adjusting.

Rotating the coarse sensitivity adjustment control in the clockwise direction may reduce the sensitivity of the control unit. Rotate this control one section at a time, checking each time to determine whether the gain has been reduced sufficiently.

After each coarse sensitivity adjustment, it may be necessary to rezero the internal lights using the 'Set Zero' control and depress the reset button on the enclosure door.

4.3 Signal Level Indicator

This consists of a row of ten LED’s, which light in sequence from left to right, as the detected signal level increases when metal approaches the sensor. Normally none or perhaps the first 1 or 2 LED’s on the left side may be flicking ON and OFF and the last LED on the right side will be constantly ON. Upon detection of metal each LED starting from the left will individually illuminate until the last two LED’s on the right hand side are ON. This will mean that metal has been detected and the LED’s will then revert back to the normal position (stated previously). However, if the Metalarm is suffering from 'false alarms' which are of a fairly regular nature, then this indicator should be examined, since it may show more than the first one or two indicators flickering ON and OFF indicating the presence of some interference which is either mains or airborne. Rotating VR10 clockwise may reduce the effects of this. The signal level should now move to the left until only 1 or 2 indicators are on. Care should be taken to not rotate this control further than necessary, since it does reduce the sensitivity of the unit.

The setting for this control can be measured with a voltmeter between test points TP0 and TP19. The default value is 180mV.

MA3000


4.4 Electronic Board - Mounted switches - (See Figure 8.)

Figure 8 For the position of the switches, which control additional optional features, refer to figure 8 above.

SW1 Selection of voltage - 115V or 230V 50Hz or 60Hz AC

SW2 (1) Brown - This prevents the metal detector being reset when metal is still in the field of the search coil - Can only be used when the conveyor belt stops immediately after metal is detected - to ensure all metal has been removed before the conveyor belt can be restarted.

(2) Red -Fail Safe Operation. - This powers up the 'Detect' relay immediately power is connected to the control unit rather than when metal is detected. When metal is detected therefore the 'Detect' relay drops out. Similarly if power to the unit fails the relay also drops out - creating a fail safe mode.

All controls on SW2 are off in the 'up' position and 'on' when in the down position.

SW4 This separates the TX and RX coil connections when switched to position 2 and is used when separate search coils are used for transmitting and receiving, such as to create an even search field or where magnetic ores are being processed.

SW5 Test button.

SW6 This, when switched 'on', i.e. in the ‘up’ position, reduces the integrator speed. This facility is used where belt speeds are slow, such as in the Wood Industry and where noise levels are high.

5.0 ELECTRONIC CIRCUIT BOARD REPLACEMENT Normally, access to the electronics is not required but if the circuit board requires replacement, the following procedures must be used.

Turn off the mains supply to the control unit and disconnect all terminal blocks connected to the base of circuit board by pulling downwards.

Undo the three panel fixing clips by turning a 1/4 turn anti-clockwise.

Undo the five screws holding the two mounting brackets and remove.

Undo the five pillars and three mounting screws. Remove the circuit board and inspect the enclosure. Remove any foreign material such as loose pieces of metal filings or wire cutting etc.

Install the new circuit board in the reverse procedure of above. Refer to section 4 for testing and operation.

SW1

MA3000


6.0 WIRING TO THE CONVEYOR MOTOR CONTACTOR To stop the conveyor drive motor when metal is detected, connect the Metalarm normally-closed relay contacts (terminals C and N/C on (TB2)) in series with the conveyor motor contactor, KM1, as in Figure 9.

After removing the metal, if the system is wired as shown in Fig 9, the conveyor will not restart until the Metalarm control unit is reset AND the conveyor motor start switch is depressed.

Figure 9

Note: If the metal detector is operated in ‘fail-safe’ mode, then the wire connected to pin 1 of TB2 should be moved to pin 3, as the relay will change polarity when power is applied to the control unit.

TB1

TB2

1 2 3 4 5 6

230

1 2 3 4 5 6 7 8 9 10 11 12

E E N L

STOP START SAFETY STOP

KM1

KM1

N/C C N/O N/C C N/O N/C C N/O

KM1

M

L1

L2

L3

MA3000


7.0 AUXILIARY RELAY An auxiliary relay is necessary between the Metalarm Control Unit and the motor starter when the motor wiring system is a fully three-phase delta with no star-point and uses a motor starter with a 415V coil.

The 415 volt motor starter coil exceeds the maximum voltage rating of the Metalarm output contacts, which are rated at 250V ac maximum.

An auxiliary relay or small contactor is required for the 415V ac contacts.

An auxiliary relay is also necessary when the plant switchgear is generating electrical interference or brushes are arcing, or when other electrical noise is being created.

This interference will propagate through the air and may also travel along the conductors in close proximity to the noise sources. When this occurs, interference will be fed into the Metalarm Control Unit along the interconnecting wires, and will cause false triggering.

An auxiliary relay in a separate enclosure, external to the Metalarm and separate from the main switchgear cabinet, will normally isolate the offending interference.

7.1 Auxiliary Relay Wiring

Auxiliary Relay Wiring Diagram

Note: If the metal detector is operated in ‘fail-safe’ mode, then the wire connected to pin 1 of TB2 should be moved to pin 3, as the relay will change polarity when power is applied to the control unit.

RL1

1 2 3 4 5 6

230

1 2 3 4 5 6 7 8 9 10 11 12

E E N L

RL1

N/C C N/O N/C C N/O N/C C N/O

TB1

TB2

MA3000


8.0 EARTHING OF ASSOCIATED PLANT WHEN FREQUENCY INVERTER SPEED CONTROLS ARE BEING USED.

Please note that when frequency inverter speed controls are being used in the vicinity of the metal detector all earth connections must be run independently back to a single star point as shown below:-

In addition, if filters are being used they should be mounted and connected as shown below:-

Because of the complex circuit design used in these filters an Earth Leakage Current of 8 to 80mA may be observed. It is possible that nuisance tripping of extremely sensitive type of ELCBs may occur so this figure should be considered when choosing such a device. It is important to provide well defined paths for the high frequency currents involved so, by far the best results are achieved when both filter and inverter are mounted securely on the same conducting, earthed backplate and not on rails etc.

Supply Cable The supply cable should be a stranded conductor and not a solid conductor type to achieve proper connection inside the terminal block, also cable lengths inside the wiring cabinet should be kept to a minimum i.e. cable entry to filter and filter to inverter. This will reduce the effect of radiated emissions back into the input cables.

INSTALLATION RECOMMENDATIONS FOR CONNECTING RFI FILTERS TO HIGH FREQUENCY INVERTER DRIVES

MA3000


Motor Cable Since the cable between the inverter and motor is a major source of radiated and conducted interference, it should be a screened type and as short as possible with the screen and safety earth core connected directly to the bonded earth post at one end and to the motor earth at the other. Never connect only one end of the screen to earth as this can be detrimental. (Pig tail effect). It is strongly recommended that the conducting cores (not the earth or screen) are threaded through, or, if possible, wound around an output cable filter choke as shown.

Earthing The point here is to clearly define the paths through which high frequency earth currents flow, and thereby minimise their harmful effect on other nearby, sensitive devices. All earthing leads, including filter earth, inverter earth and screened cable earths, should be as short as possible and securely fastened to the bonded backboard earth post - poor connections and loops of cable will act as aerials and pick up stray radiated emissions. Separation Keep the separation of the input and output cables as great as possible to prevent feedback. Input and motor output cables should never be run together in the same trunking or conduit.

Control Cables The control cables to the inverter or any other equipment in the vicinity are obviously highly susceptible to radiated emissions in the same way and should also never be run along side motor output cables. Multiple Inverters Where more than one inverter is used, for effective suppression, it is preferable that a separate filter should be used for each inverter.

MA3000


9.0 SUGGESTIONS FOR TROUBLE SHOOTING ENVIRONMENTAL INTERFERENCE The Metalarm Control Unit generates a high frequency alternating field within and near the sensor coil. While the field is strongest on the sensor coil face or in the throat of the sensor coil, it is inherent in the sensor coil design that a certain amount of the field exists outside of the sensor coil. Certain environmental conditions may sometimes affect this alternating field causing false and erratic signals.

If after installation the unit does not work properly, check for compliance with the following hook-up and installation details before proceeding to the specific causes of interference.

All cable connections should be tight on the terminal blocks in the control unit. Any sensor coil lead splice should be soldered and taped.

The power source cables should be isolated from varying inductive loads and should be run in a separate conduit.

The control unit should have a good electrical ground connection.

In certain locations more than one problem may exist and the problems may be interrelated.

Observing the installation site and the operation of the metal detector for repeating symptoms is very helpful in isolating the causes of the problems.

Correlating malfunctioning occurrences is invaluable for environmental interference trouble shooting. Observe whether interference occurs at certain specific times and in conjunction with specific activity.

Observe whether interference occurs when operated by certain personnel or only after physical change of the environment.

Use the following to help diagnose problems and problem sources and to implement corrective measures.

Basically environmental interference may be classified into four types, as described below:

9.1 Movement of Metal Large masses of metal such as shaker screens, metal deflection plates, vehicles etc. may affect metal detector operation even when at a considerable distance from the sensor coil.

Other smaller masses of moving metal when sufficiently close to the search unit may also cause false trips.

Interference may exist outside of the room or building and be hidden from operators view, such as vehicular traffic in an alley next to the building wall or a chain conveyor below or above the floor, or moving metal objects in an adjacent room.

Corrective Measures • Secure moving metal objects or remove them altogether if possible, or replace with a non

metallic material. Re-route vehicular traffic.

• Place a metal shield securely fastened and stationary between the sensor and the source of interference. Place a shield as close to moving object as possible. The size of the shield will depend on the size of the moving object.

• Install the metal detector in another location free from interference sources.

9.2 Intermittent loops of metal surrounding the sensor (Shorted Turns) A source of interference, which is difficult to recognise, is that of the shorted turn. A shorted turn is formed by metal pieces forming a complete path in an orientation around or near the sensor.

If this is intermittent, as in the case of two pieces of conduit occasionally touching together, the detector will trip each time the conduits make or break connections. The intermittence may be caused by physical deflection or vibration of equipment, and by expansion or contraction of metal due to temperature changes.

MA3000


The effect of the 'shorted turn' is that of a secondary 'coil' or 'turn' coupled to the metal detector sensor coil. The varying load of this secondary 'coil' when it makes or breaks is reflected to the sensor coil tripping the control unit.

The following metal objects may be part of or form a 'shorted turn' by themselves: metal framework, pipes, conduit, flexible conduit, guard railing, metal catwalks, conveyor rolls, etc.

To determine the existence of a 'shorted turn’: switch the metal detector off and disconnect the sensor lead at the terminal block. This will disconnect the sensor from the control instrument and there will be no metal detection.

Now, turn the control instrument on again and set gain control to maximum. Run operation under normal conditions and observe the signal level indicator. If the indicator is stable at this time, it is most likely that the sensor is picking up a ‘shorted turn’. However, the problem may also be a break on the sensor cable.

Check for breaks at this time and replace the cable if necessary.

If the cable is in good condition search for a 'shorted turn' as described in the following paragraph. If the level indicator is not stable at this time, the problem is likely to be due to excessive line voltage fluctuation.

To isolate and correct the 'shorted turn' problem, reconnect the sensor coil and turn off all surrounding equipment in order to eliminate any vibration.

The level indicator should settle down at this time or at least reduce the number of false trips.

Proceed by tapping on all metal objects, starting near the sensor coil and working out from there, in order to find where the break point is located. It is suggested that one person watch the level indicator on the control unit in order to observe any movement while another person is tapping on metal objects around and near the sensor coil.

In some cases, this may be several feet from the sensor coil. Sudden level indication movement when a metal object is tapped will indicate the intermittent connection. It may be possible to fix the problem by insulating or permanently securing this metal to metal connection. For example, in the case of broken weld, re-weld or in the case of a loose pipe or conduit, re-secure the holders.

9.3 Excessive Line Voltage Fluctuations Electrical interference may be in the form of line voltage 'spikes' caused on-off varying inductive loads of electrical equipment on the same power line as the metal detector, or other power lines in close proximity to the supply line for the metal detector. Corrective Measures • Use another power line, (without the varying inductive loads) for the metal detector. • Disconnect electrical equipment causing the large inductive loads. • Connect interfering electrical equipment to another power source. • Re-route the power line to the metal detector. • Install a constant voltage transformer (120 va. minimum) between metal detector and power

source. 9.4 Proximity of Severe RF Radiation Sources Electrical or electronic interference can be radiated into the sensor coil or introduced into the metal detector from other energy emitting devices such as arcing motors, arc welders, and arcing relay points.

Corrective Measures • Remove or replace equipment causing interference. • Operate welding equipment only at times when metal detector is not required to operate. Call the factory service department if unable to arrive at a satisfactory solution. Telephone: + 44 (0) 2920 868501 email: [email protected]

MA3000


10.0 MA3000 CE Case Assembly Parts List

Ref No Description Qty 01 Case fully fitted 1 02 Enclosure 400x300x150 (SS or painted steel) 1 03 Indicator Assembly (POWER). 1 04 Momentary Illuminated Switch Assembly (DETECT/RESET). 1 05 Front Door Wiring Loom 1 06 Insulated Mounting Kit 1 07 Cable Gland PG11 Brass - As req'd 08 Filament bulb MBC 2 09 Label 1 10 Door Key 1 SEARCH COIL CABLES Cable Search Coil - 1m 1 Cable Search Coil - 3m 1 Cable Search Coil - 5m 1 Cable Search Coil - 10m 1 Cable Search Coil - 20m 1

1/2

3/8

4/8

10

9

6

7

5

MA3000


MA3000 CE Electronic Assembly Parts List

Ref No Description Qty ** Electronic Unit Complete 1 21 PTL147A Printed Circuit Board 1 22 Front Panel MA3000 CE 1 23 Push Latch Arrow 2001 3 24 Bargraph Module with plug 1 25 Control knob 3 26 Plain cap for control knob 1 27 Pointer cap for control knob 2 28 Relay 4PCO 1 29 Fuse T500mA/1A 20mm 1 30 Plug 4 way 1 31 Plug 6 way 1 32 Plug 9 way 1 33 Plug 12 way 1 ** Electronic unit comprises - printed circuit board, bargraph module, front panel etc. all mounted on back plate

21

29

25/26

22

23

28

24

25/27

30

31

32 33

MA3000


11.0 TECHNICAL DATA POWER SUPPLY 115 – 230VAC VIA SELECTOR SWITCH 50/60Hz

(24VDC VERSION AVAILABLE ON REQUEST 2A STARTUP CURRENT CAPACITY REQUIRED)

POWER 11W

FUSE 1A – 500mA (115/230)

RELAY 4PCO VOLT FREE

250V/5A MAXIMUM RATING

TEMPERATURE 0 TO +50°C

MATERIALS CONTROL UNIT: POWDER COATED STEEL OR STAINLESS STEEL

SENSOR COIL: HDPE (HIGH DENSITY POLYETHYLENE)

SENSOR CABLE RG58/URM76 50 OHM CO-AXIAL CABLE

IP RATING IP66 (NEMA 4X)

Part 11 Metal Detector Manual

Documents