#  **Coil Power Supply Procedures**

August 7, 2002

A. Godley, J. Meier, J. Nelson, E.A. Peterson

### **Personnel Safety** 

OSHA defines 3 levels of regulatory exposures for static magnetic
fields. The lowest is 5 gauss for exposure to people with cardiac
pacemakers. All detector decks south of the 2^nd^ pillar of SM2 (i.e.
12ft north of the end of SM1) were near or above 5 gauss. A crash button
is mounted in the workstation area outside of this field perimeter.

The highest field (500 gauss) is where the wires leave the borehole and
bend down to vertical. This is below either of the other two OSHA
regulatory thresholds (600 gauss for continuous whole body exposure and
6k gauss for extremities).

There are no restrictions for people working in the detector area
without cardiac pacemakers. People with pacemakers should not enter the
detector area while the red field-on warning lights are flashing.

### **Fields in Areas Used for Rigging and Construction**

At the north face of SM2 we measured the field in a number of locations
when 10 planes were in place. Here the field fell off to below the
Earth's field when more than 10 cm away from the steel. Anywhere on the
face of the plate more than 1cm from the edge had fields consistent with
the Earth's magnetic field. These fields were low enough to not require
any restrictions on rigging at the north of the detector face.

The fields were measured on the access bridge, the south storage area
(\<8 gauss), and the forklift isle (\<5 gauss) and are low enough that
there are no rigging restrictions in these areas while the coil is
energized.

The fields inside the inter-SM gap and near the south coil turns are
high enough that the coil should be powered down before any large steel
object (e.g. the crane hook) are moved in the area. Electrical LOTO
procedures apply in this situation.

For electrical safety we require that, except in exceptional situations,
the coil should be turned off for any work near the trench under the
detector, near the turns in the SM gap, or near the turns at the south
end of the detector. Standard electrical LOTO procedures may apply.
Exceptional situations may require work to be done in these areas with
the coil powered. This can only be done with supervisor approval.

## ***LOCAL CONTROL***

## ***Procedure for turning on the coil at the power supply***

Equipment: You will need a multi-meter.

1.  The coil power supply is located at the southwest end of SM1 in the
    lower deck, inside an orange cabinet.

2.  Ensure the switch on the bottom left of the cabinet front is off, as
    well as the main 480 V switch. Check that the crash button is pulled
    out (located at the bottom of the west side stairs near workstation
    1).

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2.  Open the cabinet and then swing out the regulator board.

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3.  There are two switches on this board. Their functions are printed on
    the circuit board.

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4.  The lower switch sets the mode of the power supply between voltage
    supply (up) and current supply (down) modes. It should always be in
    current mode.

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5.  The upper switch sets the supply to internal (up) or external (down)
    reference. This switch is inside so as not to get bumped. If the
    coil was to switch references whilst on, the result could be quite
    bad, e.g. consider that the internal reference is 80A and the
    external is 0A.

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6.  Move the upper switch to internal reference mode (up).

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7.  Close and latch the regulator board and close the cabinet door.

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8.  Turn the switch on the front of the cabinet to LOCAL.

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9.  Check that the ten turn pot is set to zero (fully anti-clockwise).

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10. Lift the main 480 V switch, and the one on the front of the cabinet.
    Use standard electrical LOTO for the 480 V switch. You should hear
    the fans start up, and the 6 red field-on warning lights will start
    flashing. The crash button will also light.

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11. Check that the following LEDs are on: Control Powered, DC Clamped
    Out.

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12. Press RESET to reset the interlocks. All but the DC ON LED will be
    illuminated.

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13. Press ON. You will hear the connection to the 480 V transformer
    being made and the DC ON LED will light.

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14. Insert the probes of the multi-meter into the plugholes above the
    ammeter. 1 V here is equivalent to 20 A through the coil.

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15. Bring the coil current up with the ten turn pot, pausing a 30
    seconds every 20 A, up to 80 A.

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16. The ammeter on the supply is not accurate. Use your multi-meter!

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17. The voltage required to induce an 80 A current through the coil cold
    is around 228V. Check this.

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18. The coil is now running smoothly. Go up to the DCS computer in the
    control room and check that the current graph is steady at 80 A. The
    voltage and thermocouple graphs will rise for 5 to 7 hours.

### **LOCAL CONTROL**

### **Procedure to turn off coil** 

1.  Slowly turn the ten-turn pot anti-clockwise, down to zero. From 80
    A, take about 30 seconds to do this.

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2.  Press the OFF button.

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3.  Flick the cabinet 480 V switch off and pull down the main 480 V
    switch.

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4.  Lock the main 480 V switch. Standard electrical LOTO should apply.

## 

### **LOCAL: Procedure to switch the magnet's polarity**

1.  At the power supply cabinet, slowly turn the ten-turn pot
    anti-clockwise, down to zero. From 80 A, take about 30 seconds to do
    this.

2.  Press the OFF button.

3.  Locate the reversing switch as the first box on top of the coil
    power supply cabinet. In the front panel, there are three lights
    corresponding to

    1.  "timer running"

    2.  "forward"

    3.  "reverse".

4.  Only the light corresponding to the current magnet polarity will be
    lit. To the right, there can be found the polarity switch and the
    local/remote control switch.

5.  Flip up the local/remote switch to LOCAL.

6.  Flip the forward/reverse switch to the desired polarity. Supposing
    the original polarity is FORWARD The lights will follow the
    sequence:

    i.  1\) and 2) on

    ii. 1\) on

    iii. 1\) and 3) on

    iv. 3\) on.

7.  After about 1 minute, the sequence is completed. To avoid power
    supply trips, wait 3 more minutes before proceeding.

8.  Follow steps 13-18 in "Local: Procedure to turn on the coil at the
    power supply" to bring the magnet back up to the operating current.

9.  The magnet should be now operating with reversed polarity. Follow
    the same procedure if you wish to restore the polarity to its
    original status.

## ***REMOTE CONTROL***

## 

## ***Procedure for turning on the coil at the power supply***

1.  Ensure the switch on the bottom left of the cabinet front is off, as
    well as the main 480 V switch. Check that the crash button is pulled
    out (located at the bottom of the west side stairs near workstation
    1).

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2.  Open the cabinet and then swing out the regulator board.

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3.  There are two switches on this board. Their functions are printed on
    the circuit board.

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4.  The lower switch sets the mode of the power supply between voltage
    supply (up) and current supply (down) modes. It should always be in
    current mode.

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5.  The upper switch sets the supply to internal (up) or external (down)
    reference. This switch is inside so as not to get bumped. If the
    coil was to switch references whilst on, the result could be quite
    bad, e.g. consider that the internal reference is 80A and the
    external is 0 A.

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6.  Set the reference switch to external (down).

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7.  Close and latch the regulator board and close the cabinet door.

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8.  Turn the switch on the front of the cabinet to REMOTE.

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9.  Lift the main 480 V switch, and the one on the front of the cabinet.
    Standard electrical LOTO should apply to this switch. You should
    hear the fans start up, and the 6 red field-on warning lights will
    start flashing. The crash button will also light.

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10. Return to the DCS computer in the control room.

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11. In the *MagNet Control* window, enter the password \"operator1\".
    The password is required for controlling the supply and will expire
    after 3 minutes, denying access to the coil controls until the
    password is re-entered.

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12. Click the RESET button. The Magnet Power Supply Control display
    should show: Ready, DC Off, Remote

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13. Click the ON button. This will turn the supply on, which used to
    disrupt the FieldPoint unit. All the display boxes went red, but
    returned all green within a minute. This was fixed by powering the
    FieldPoint through a UPS.

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14. Click CHANGE CURRENT and enter 20 in the dialog box.

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15. When the *Magnet Current (Am)* field value stabilizes, click CHANGE
    CURRENT again, and enter 40, then 60 then 80. Monitor the current
    and voltage graphs to make sure there is no more than a 2A
    overshoot. The voltage required to induce an 80A current through the
    coil cold is around 228 V. Check this value.

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16. The coil is now running smoothly. The voltage and thermocouple
    graphs will rise for over 5 to 7 hours.

### **REMOTE: Procedure to turn off coil** 

1\. At the DCS computer in the control room, enter the password
"operator1".

2.  Click CHANGE CURRENT and enter 60 in the dialog box.

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3.  When the *Magnet Current (Am)* field value stabilizes, click CHANGE
    CURRENT again, and enter 40, 20 then 0. It will take about a minute
    to die down.

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4.  Click the OFF button, and type \"yes\" when prompted.

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5.  Proceed down to the coil supply cabinet then flick the cabinet 480 V
    switch off and pull down the main 480 V switch.

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6.  Lock the main 480 V switch and use standard electrical LOTO.

### 

### **REMOTE: Procedure to switch the magnet's polarity** 

1\. At the DCS computer in the control room, enter the password
"operator1".

3.  Click CHANGE CURRENT and enter 60 in the dialog box.

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4.  When the *Magnet Current (Am)* field value stabilizes, click CHANGE
    CURRENT again, and enter 40, 20 then 0. It will take about a minute
    to die down.

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5.  Click the OFF button, and type \"yes\" when prompted.

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6.  When the *On/Off Status* shows DC OFF on a red background , press
    the REVERSE button [once]{.underline}. In less than a minute, the
    *Polarity Status* field will display REVERSE or FORWARD if the
    original status was FORWARD or REVERSE respectively. To avoid Power
    Supply trips, wait at least 4 minutes after you pressed the REVERSE
    button before proceeding.

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7.  Retype the password, if necessary, and click the ON button. Wait
    until the *On/Off Status* field is back to DC ON over a green
    background. Ignore the error message "can not turn on magnet, check
    the fieldPoint module" and click ok.

8.  Click CHANGE CURRENT and enter 20 in the dialog box.

9.  When the magnet current value stabilizes, click CHANGE CURRENT
    again, and enter 40, then 60 then 80.

10. The magnet should be now operating with reversed polarity. Follow
    the same procedure if you wish to restore the polarity to its
    original status.

### 

### **Crash button information**

1.  The Crash Button is located at the bottom of the west staircase near
    workstation 1 next to the fire extinguisher.

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2.  It is illuminated as soon as the 480 V switch for the supply cabinet
    is turned on.

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3.  Pushing the button in will stop the current flow in the coil. The
    entire 480 V section of the supply will be dead. The 6 magnetic red
    field-on warning lights will stop flashing.

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4.  To restart the supply:

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1.  Pull the crash button back out.

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2.  Ensure the set current is zero, either locally or remotely,
    depending on where it is being controlled.

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3.  RESET it there too.

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5.  The supply can then be turned ON, and the current ramped up. (See
    above.)