KAGRA VIS Operations Manual - LVDT

LVDTs are used for vertical sensing and actuation in all the GAS filters and for horizontal sensing and actuation in all the IP stages.

See LVDT Signal Conditioning for useful background on LVDT demodulation.

See JGW-T1201255 for description of the Nikhef-supplied cards, and JGW-T1604798 for more information on how to tune the demodulation circuit.

LVDT Calibration Procedure: JGW-E1707287 or LVDT Calibration Procedure.

Type A

Your data here!

Type B Data

LVDT Drivers Data

For SR2:

LVDT Driver S.N.

Left card

Stage

Resistor value [ohm]

Reference Signal

Gain

Right card

Stage

Resistor value [ohm]

Reference Signal

Gain

SR2: SN 7777777

R0

BF GAS

59.2

4. Vpp

4./5.02 = 0.

R0

PI LVDT#1

50.1

4. Vpp

4./5.02 = 0.

R1

SF GAS

36.3

4. Vpp

4./5.02 = 0.

R1

PI LVDT#2

50.6

4. Vpp

4./5.02 = 0.

R2

F0 GAS

59.6

4. Vpp

4./5.02 = 0.

R2

PI LVDT#3

51.2

4. Vpp

4./5.02 = 0.

R3

Not used

59.5

4. Vpp

4./5.02 = 0.

R3

Not used

50.0

4. Vpp

4./5.02 = 0.

For SR3:

LVDT Driver S.N.

Left card

Stage

Resistor value [ohm]

Reference Signal

Gain

Right card

Stage

Resistor value [ohm]

Reference Signal

Gain

SR3: SN 1807783

R0

BF GAS

60.0

4.90 Vpp

4.90/5.02 = 0.976

R0

PI LVDT#1

50.7

4.90Vpp

4.90/5.02 = 0.976

R1

SF GAS

60.7

4.86 Vpp

4.86/5.02 = 0.968

R1

PI LVDT#2

50.7

4.88 Vpp

4.88/5.02 = 0.972

R2

F0 GAS

60.9

4.86 Vpp

4.86/5.02 = 0.968

R2

PI LVDT#3

50.0

4.88 Vpp

4.88/5.02 = 0.972

R3

Not used

60.7

4.86 Vpp

4.86/5.02 = 0.968

R3

Not used

50.9

4.86 Vpp

4.86/5.02 = 0.968

For SRM:

LVDT Driver S.N.

Left card

Stage

Resistor value [ohm]

Reference Signal

Gain

Right card

Stage

Resistor value [ohm]

Reference Signal

Gain

SRM: SN 1807786

R0

BF GAS

60.6

5.04 Vpp

5.04/5.04 = 1.0

R0

PI LVDT#1

50.0

5.0 Vpp

5.0/5.04 = 0.992

R1

SF GAS

60.1

4.96 Vpp

4.96/5.04 = 0.984

R1

PI LVDT#2

50.0

4.92 Vpp

4.92/5.04 = 0.976

R2

F0 GAS

60.7

4.96 Vpp

4.96/5.04 = 0.984

R2

PI LVDT#3

50.5

4. Vpp

5.0/5.04 = 0.992

R3

Not used

61.2

4.94 Vpp

4.94/5.04 = 0.98

R3

Not used

50.8

4. Vpp

4.9/5.04 = 0.972

New box for SRM. Adjusting the potentiometers to have the same values:

LVDT Driver S.N.

Left card

Stage

Resistor value [ohm]

Reference Signal

Gain

Right card

Stage

Resistor value [ohm]

Reference Signal

Gain

SRM: SN 1403020

R0

BF GAS

60.2

- Vpp

- = -

R0

PI LVDT#1

50.4

- Vpp

- = -

R1

SF GAS

60.1

- Vpp

- = -

R1

PI LVDT#2

50.3

- Vpp

- = -

R2

F0 GAS

60.7

- Vpp

- = -

R2

PI LVDT#3

50.3

- Vpp

- = -

R3

Not used

61.0

- Vpp

- = -

R3

Not used

50.2

- Vpp

- = -

Yoke Height Settings

The yoke should be set so that the double and single LVDT coils are symmetrically aligned when the keystone is at nominal height. It is convenient to set this in terms of the amount the PEEK coil former sticks out above the filter baseplate.

Bottom Filter (BS and SRx)

Note that the CAD is wrong for the bottom filter yoke:

YokeHeightExample.pngKeystoneHeightExample.png

Standard Filter (BS and SRx)

YokeHeightExampleSF.png

Top Filter (BS and SRx)

Summary

GAS Filter

Yoke Height

Keystone Height

BS BF

3.5 mm

65.5 mm (up from baseplate)

SR BF

3.5 mm

65.5 mm (up from baseplate)

BS SF

6 mm

65.5 mm (up from baseplate)

SR SF

6 mm

65.5 mm (up from baseplate)

BS F0

36 mm

153 mm (up from top plate), 16.5 mm (down from ring)

SR F0

34 mm

153 mm (up from top plate), 16.5 mm (down from ring)

Type Bp Data

Your data here!

Stocktake

LVDT Stocktake as at 2018-04-13

See JGW-D1402826-v2: LVDT Driver Module Top Assembly.

* = sighted recently

Faulty (3)

In use, presumably OK (14)

In use, needs new front panel (1)

In circuit room (11)

In circuit room, needs new front panel (1)