Study of Electrical Noise
Induced by Synchrotron Radiation

Yasuhide Ishizawa, Toru Ohata
JASRI/SPring-8
Controls and Computing Division
April 12-16, 2010
Daejon, Korea

Outline• Problem: unstable X-ray intensity• Tools for noise study• Result of noise measurements• Solution• Conclusion

Problem: unstable X-ray intensity
staff’s voice
Repeatedfor 14 years

We don't know why,
but X-ray intensity fluctuates.

Temporal X-ray stabilizationby components tuning.

We need fundamental solution!

Motor Control System & Beamline Components
Motor Control System

Motor drivers

Motor control cardconnector box

VME system
Beamline components

to stepping motor

16 motors
X-rayNS
Undulator

Double-Crystal
Monochromator

Experiment

Problem: unstable X-ray intensity(continued)• Problem1– The motor attached to the monochromator
moved without any control pulse.
• Problem2– Electronic devices sometimes broken.
(ex. VME card)• Previous experience– Cable charged up by noise induced bysynchrotron radiation» We modified cables, ground and circuits.

We started the noise investigation.

Assumption : １
Photoelectric effectcable
Monochromator

ConnectorMotorboxdriverVME

in vacuum
motor

X-rayelectron

Strong X ray kicks
out electron byphotoelectric effect.

Assumption :2
Charge up
cable
Monochromator

Connector
Motorbox
driverVME

in vacuum
motor
electrons

Electrons charge up
the material somewhere.

Assumption :3
Discharge
cable
Monochromator

Connector
Motorbox
driverVME

in vacuum
motor

The electricity accumulate
in monochromatordischarge

Assumption :4
Noise
cable
Monochromator

Connector
Motor
box
driverVME

in vacuum
motor

Noise surge propagate
through control line.

Assumption : 5

NoiseMotor movecable
Monochromator

Connector
MotorboxdriverVME

in vacuum
motor

Motor-driver misreads thenoise as the drive signal.
→ Motor move theaccidentally X-ray
intensity fluctuates

Assumption : 6Broken!

Noise damages electric devices
cable
Monochromator

Connector
MotorboxdriverVME

in vacuum
motor

VME card and connector
box are broken by noise.

Tools for the noise studyWe used three tools
Power quality analyzer
AC power quality
Close Field Probe
Magnetic field

Clamp on Noise Sensor
Noise in signal/power cable
Powerful tool for noise study!

AC Power quality analyzer
VMEconnector
boxMotordriver
Motor

LNG

Power quality analyzer 3197
measurement instrument to monitor andanalyze•AC voltage•Frequency•Waveform•Current value•Harmonic•etc,I find power line no problem.

HIOKI

Magnetic near-field probe
VME
connector
box

Motordriver

Motor

9 kHz – 1GHz

oscilloscope

11941A Close Field Probe
measures magnetic field radiationfrom surface currents, slots, cable.
HP Agilent
Joint slot for the maintenance

Quantitative measurement difficult.

CLAMP ON NOISE SENSOR
VME
connector
box

HiLOGGER3145 can measure
the noise levels and frequencies onsignal, power and grounding lines
connected to electronic devices.

Noise sensor 9754
HIOKI

Motordriver

Motor

CLAMP ON NOISE SENSOR
VME
10[A]

15kHz
15kHz
70kHz
70kHz
250kHz250kHz
1MHz
1MHz
5MHz
5MHz
20MHz
20MHz
60MHz
60MHz

connectorbox

1.0

CLAMP ON NOISE SENCER

Motordriver

[A]
101.0

HiLOGGER3145
0noiselevels and frequencies on0 10 20 30 40 50 60 70 80 90
telecom,
power andgroundinglines
minute(Time)connected to electronic devices.
Display real-time peak-to-peakvalue in 7 frequency band onlevel meters.
CLAMP ON NOISE SENOER

５10 15 20

Hour (Time)
Please examine
specs.

Noise measurement

Correlation between noise and undulator gap
Connector
box
VME

50mm
11.32mm02000← この間 →
ノイズが発生していない
6000 8000

4000
Gap
Time(Sec)

1*104

0GapNSSNS

N S N
Undulator

Gap open → Low flux
Gap close → High flux

MotordriverStepping
motor★

Correlation between noise and undulator gap
Connector
box
VME

Motor
driverStepping
motor★

Gap and cable noise
50mm
11.32mm(A)← この間 →
ノイズが発生していない

0Low flux: no noiseHigh flux: high noiselevelThe noise is correlatedwith high X-ray flux.

Correlation noise
Connector box
VME← この間 →ノイズが発生していない

Motordriver

Steppingmotor★

Correlation noise
Connector box
VME← この間 →ノイズが発生していない

When this noiseoccurred ,noise (★) was found.

★

Motordriver

Steppingmotor★

Large noise measured
VME

5V
Connectorbox

Motordriver★

Stepping
motor

PRINT_02

10

Large noise

oscilloscope
Volt voltage
Noise

8

Voltage of a motor
control signal（V） 6
5V constant voltage with noise4★
Waveform : showering noise
Frequency: about 1 MHｚ
Amplitude: over 12V

20-2-4-6-6-2-210 -1-1
10０0-61１10

μsec-62２10-6-63３10 4４10

Measured minimum pulse
Motordriver

Motor driven byone minimum pulse
Pulse Generator

6（V）

420-1

Pulse width: 216nsec
Voltage : 3.3V01
Secondμsec

SteppingmotorComparison between showering noise and signal
Motor driven by
one minimum pulse
PRINT_02

showering noise
10Volt8（V）

66442

200-2-10 1
Secondμsec-4-6-6-2 -210 -1 -1
100０-61１10

μsec-62２10-63３10-64４10

Comparison between showering noise and signal
Showering noise

10

Minimum pulse
86Showering noise is over
Minimum pulse voltage.

V 42Showering noise drive themotor 2 pulses.

0-2-4-2-10

1
μsec

234

Noise measurement results• The noise is generated when strong
X-ray.

• Main component of electric noise isabout 1MHz.
• Large electric noise can move a motor.

Solution

Strategy• Separation strategy– Separate monochromator distant from the motor
control devices– Stop noise current penetrating into control system!
VMEConnector
Driverbox

Motor Control Devices

separation in vacuum

motorStopnoise

Monochromator

We try to use ferrite core for noise reduction.

Ferrite core
• We selected ferrite core.

noise
frequency

100

D:32mmImpedance (Ω)

w:160mm

1000
model number: FT3KM S11080HB
quality of material : FINEMET
Hitachi metals

100 1000 10000
Frequency (kHz）impedance character

This ferrite core is the simple
solution to reduce the noise.

Prevent inrush electric noise
into control system by using ferrite core
TurnNum-bersConnector box
DriverVME

0 turnferritecore motor★

0 turnNoise is eliminatedover 2turn

１turn

2turn

3turn
２Impedance = an Impedance × N
N = turn number

The noise was not
dropped over 2 turns.

Installation Problems
It was not practical for us!

• There are not enoughspace for core.
• Cable winding isdifficult.

We searched the new core to installeasily to existing cables

Ferrite core sellection

PE22
TDK

FINEMET
Hitachi metals

Installationeasy

difficult

Impedance
character20Ω :1MHz:1turn38Ω :1MHz:1turnNoise reduction

Not-measure

2turn is enoughTotal Impedance

20Ω× 8 piece=160Ω ≒ 152Ω←38Ω× 2turn2

8 pieces of ferrite core clumps cables with 1 turn２

Impedance = an Impedance × N
N = turn number

Installation of Ferrite coreferrite core

PE22 TDK

16 cables• We can install the ferrite core, easily.
– 8 cores clamped 16 cables.

• NO noise.
• X-ray intensity stabilized.

8 piecescables

SPring-8 staffs and users
become very HAPPY!
bottom view

Conclusion••

The noise is generated when strong
X-rays.
Main frequency of electric noise is about1MHz.
•Motor-driver mistakes the noise for the drivesignal.
–Problems of motor malfunction is solved byinstalling ferrite core.
–No noise.
Please contact mewhen there is a similar case in your institute.