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
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