Unwind Drive Cooling Fan

©Bill Kilbey 2009

High 1x Cooling Motor/Fan

• Motor/fan sit on top of large variable speed motor, fan mounted directly on motor shaft

• The fan is subject to buildup of dirt/product• 1x TS dominant with amplitudes increasing• Attempt to balance was not successful

– Varying amplitude 1mil pk-pk to 7mils pk-pk– Unstable phase ±100⁰

High 1x TSS1 - WINDER UNWIND DR COOLING FAN

2PM UDCF -BH MTR. INBOARD BRG. HORIZ.

Route Spectrum 16-Oct-09 09:21:49

OVERALL= .7546 V-DG PK = .7514 LOAD = 100.0 RPM = 1770. (29.50 Hz)

0 20000 40000 60000 80000

0

0.2

0.4

0.6

0.8

1.0

Frequency in CPM

PK

Vel

oci

ty in

In/S

ec

Freq: Ordr: Spec:

1822.5 1.030 .699

Unsuccessful balance attempt

• Amplitude and phase both unstable• I tried the lowest filter band % on the tach,

still no luck

High Resolution SpectrumS1 - WINDER UNWIND DR COOLING FAN

2PM UDCF -AH MTR. OUTBOARD BRG. HORIZ.

Analyze Spectrum 16-Oct-09 09:15:17

PK = .6680 LOAD = 100.0 RPM = 1770. (29.50 Hz)

0 3000 6000 9000 12000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Frequency in CPM

PK

Vel

oci

ty in

In/S

ec

Freq: Ordr: Spec:

1773.7 1.002 .638

High Resolution Spectrum ZoomS1 - WINDER UNWIND DR COOLING FAN

2PM UDCF -AH MTR. OUTBOARD BRG. HORIZ.

Analyze Spectrum 16-Oct-09 09:17:00

P-P = 8.38 LOAD = 100.0 RPM = 1770. (29.50 Hz)

1740 1760 1780 1800 1820

0

3

6

9

12

Frequency in CPM

P-P

Dis

pla

cem

ent

in M

ils

1773

.0

1768

.8

Freq: Ordr: Spec:

1769.1 .999 1.624

Spectrum from other cooling fanS1 - WINDER UNWIND DR COOLING FAN

3PM UDCF -AH MOTOR OUTBOARD BRG HORZ.

Analyze Spectrum 16-Oct-09 09:27:06

PK = .3501 LOAD = 100.0 FPM = 3540. (1770. RPM)

1750 1760 1770 1780 1790 1800 1810

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Frequency in CPM

PK

Vel

oci

ty in

In/S

ec

1769

.3

1773

.1

Freq: Ordr: Spec:

1772.8 1.002 .204

Calculations

• 1773.1 – 1769.3 = 3.8 RPM Delta (.063 Hz)• The inverse of Diff. F1-F2 = T beat• T beat = 15.8 secs. approx.

Time waveform beat on #2S1 - WINDER UNWIND DR COOLING FAN

2PM UDCF -AH MTR. OUTBOARD BRG. HORIZ.

Analyze Waveform 16-Oct-09 09:15:17

RMS = .2380 LOAD = 100.0 RPM = 1770. (29.50 Hz)

PK(+) = .5407 PK(-) = .6437 CRESTF= 2.70

0 4 8 12 16 20 24 28 32

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

Time in Seconds

Acc

eler

atio

n in

G-s

Time waveform beat on #3S1 - WINDER UNWIND DR COOLING FAN

3PM UDCF -AH MOTOR OUTBOARD BRG HORZ.

Analyze Waveform 16-Oct-09 09:27:06

RMS = .1311 LOAD = 100.0 FPM = 3540. (1770. RPM)

PK(+) = .2954 PK(-) = .3219 CRESTF= 2.46

0 10 20 30 40 50 60 70

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

Time in Seconds

Acc

eler

atio

n in

G-s

Time: Ampl: Dtim: Freq:

37.73 .201 15.63 3.838

approx. 15 sec beat

#2 PM Fan

#3 PM Fan

Conclusions• The cooling fans are exciting resonances of the

respective motor and foundation. You can feel the vibration and beat in the floor.

• The 2 fan speeds are beating, they are physically locate 30’ apart.

• Band filter on tach is not fine enough to separate 4 RPM.

• Rebalance attempt on day when both can be shut down.

• Investigate foundation and structure for resonance.

Update 11/3/09

• #2 is shut down, so no beat. Can not shut down #3 for balance.

• Data shows bearing may be slightly loose in housing.– RBPF and 1x TS sidebands have increased– PeakVue has High 1x TS and small bearing defects.

• Looseness may contribute to phase/amp instability.

Balance Reference Run

• Original with beat 5.5 mils @ 236• Today with no beat 3.3 mils @135

Rotor Bar Pass Freq. w/sidebands 1xTS

RM

S A

ccel

erat

ion

in G

-s

Frequency in Orders

S1 - WINDER UNWIND DR COOLING FAN3PM UDCF -AH MOTOR OUTBOARD BRG HORZ.

0 30 60 90 120

Max Amp .91

Plot Scale

0

1.0

09:38:0203-Nov-09

11:07:0917-Jul-09

16:57:4503-Feb-09

S1 - WINDER UNWIND DR COOLING FAN3PM UDCF -AH MOTOR OUTBOARD BRG HORZ.

Route Spectrum 03-Nov-09 09:38:02

OVERALL= .3221 V-DG RMS = 1.12 LOAD = 100.0 FPM = 3542. (1771. RPM)

0 10 20 30 40 50

0

0.3

0.6

0.9

1.2

Frequency in Orders

RM

S A

ccel

erat

ion

in G

-s

32.0

433

.04

35.1

036

.11

37.1

0

Ordr: Freq: Spec:

1.000 1770.8 .09982

S1 - WINDER UNWIND DR COOLING FAN3PM UDCF -AH MOTOR OUTBOARD BRG HORZ.

Route Spectrum 03-Nov-09 09:38:02

OVERALL= .3221 V-DG RMS = 1.11 LOAD = 100.0 FPM = 3542. (1771. RPM)

28 32 36 40 44

0

0.3

0.6

0.9

1.2

Frequency in Orders

RM

S A

ccel

erat

ion

in G

-s

32.0

4

33.0

4

35.1

0

36.1

1

37.1

0

Ordr: Freq: Spec: Dord:

37.15 65792. .238 1.018

PeakVue 1x TS and harmonicsS1 - WINDER UNWIND DR COOLING FAN

3PM UDCF -AH MOTOR OUTBOARD BRG HORZ.

Analyze Spectrum 03-Nov-09 09:38:26 (PkVue- HP 500 Hz)

RMS = .6700 LOAD = 100.0 FPM = 3540. (1770. RPM)

0 2 4 6 8 10

0

0.1

0.2

0.3

0.4

0.5

0.6

Frequency in Orders

RM

S A

ccel

erat

ion

in G

-s

1.00

2.07

3.07

4.07

8.14

.07

1.07 2.

00

5.07

7.13

Ordr: Freq: Spec:

.996 1762.5 .412

2 x Line Frequency

BPFO

BSF