Electrical_Signature

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Electrical Signature Analysis

POSTMA & POSTMA

(PTY) LTD.

Motor Current Signature Analysis (MCSA) is a commonly miss-used term within industry. MCSA refers to the evaluation of current waveforms only, including the demodulation of the current waveform and FFT analysis. Electrical Signature Analysis (ESA) is the term used for the evaluation of the voltage and current waveforms. This provides an increased advantage to diagnostics as power related, motor related, and load related signals can be quickly filtered. It also provides several unique abilities when related to power quality, DC motor analysis, generator analysis as well as other advantages. ESA is a system used for analyzing or trending dynamic, energized systems.

Capabilities

Complete harmonic analysis of every cycle of all phases, simultaneously.
Swell, sag and inrush detection of every half cycle of all phases, simultaneously.
Complete power/energy/cost analysis while simultaneously doing harmonic, swell sag and transient analysis on all inputs.
Compatible with variable frequency drive outputs to systems over 400 Hz and DC.
Data logging.
Automatic rotor bar and stator deterioration and severity there of.
Automatic rotor-stator eccentricity characteristics.
Automatic motor speed and slip.
Average running current to variation – an indicator of motor torque variation.
Power factor.
Torsional vibration and dynamic loading.
Automatic misalignment and mechanical unbalance.
Bearing degradation and automatic bearing fault indication.
Current/Voltage variations and THD.
Current demodulation and analysis.
Motor efficiency calculations.

Typical reports generated by the system

Report A (Problem motor)

Performance Summary

Bottom Line

This motor is operating normally, no action is required.

This motor exhibits suspicious operation, trending of the motor is warranted.

X This motor exhibits abnormal indications, action is warranted, NOW.

Power Factor Commentary

Power factor exceeds 0.85.

X Power factor is below 0.85, see detailed report.

Current Commentary

X Current variation is within normal limits.

Current variation is beyond normal limits, see detailed report.

Voltage Commentary

Voltage variation is within normal limits.

Voltage variation is beyond normal limits, see detailed report.

X RMS voltage differs from nameplate by more than 5%.

Load Commentary

X L oad on the motor is consistent with nameplate values.

Load on the motor exceeds nameplate values, see detailed report.

Load on the motor is less than 25%.

Phase Connection Commentary

X Connections are normal.

Voltage ground reference is NOT neutral.

Loose connection.

Rotor Commentary

X Rotor bar health is normal.

Rotor bar health is questionable, see detailed report.

Load is insufficient to determine rotor bar health, at this time.


Stator Commentary

X Stator health is normal.

Stator mechanical health is questionable.

Turn to turn short.

Rotor/Stator Air-gap Characteristics

X Dynamic or static eccentricity indications do not exist.

Indications of static eccentricity exist.

Indications of dynamic eccentricity exist.

Harmonic Distortion Commentary

X There is no evidence of harmonic distortion.

There is evidence of harmonic distortion, see detailed report.

Misalignment Indications

X There are no indications of mechanical problems like misalignment or unbalance.

There are indications of mechanical problems like misalignment or unbalance.Perform vibration survey to identify and correct the cause.

Bearing Commentary

There is no evidence of bearing problem.

X Indications of potential bearing problems, perform vibration survey to verify.

INPUT SUMMARY

NAMEPLATE INFORMATION

    Units 
Manufacturer ****   
Serial Number ****   
Model Number ****   
Motor type Synchronous   
Power 37.0 KW 
RPM 2965 Rpm 
AC/DC AC   
Poles 2   
Phases: 3   
Voltage 380.0 Volt 
Full Load Current 69.50 Amp 
Number of stator slots 30   
Number of rotor bars 26   
Torque 119  N.m 
CT Ratio 1.000   
PT Ratio 1.000   
Duty Cycle ****   
Service Factor 115   
Frame Size ****   
Insulation Type ****   
Ambient Temperature 70.0 F° 
Motor efficiency -1.000   
Power factor 0.870

Detailed Calculations

LEGENDS:

Impedance = Complex Impedance = vi/ci

CF = Crest Factor = (waveform peak)/(waveform rms)

CFC = Carrier Frequency Content = 10^(x/20)/frms, %

THDF = Transformer Harmonic De-rating Factor = sqrt(2)/CF, %

VDF = Voltage De-rating Factor = 100 - (voltage unbalance, %)^2, %

Se, fund = Location of pole pass frequency fundamental, Hz

Se, harm = Number of pole pass frequency harmonics

Level = Sum of spectral amplitudes of pole pass frequency fundamentals and

harmonics

Slip = SRSS sum of slip and harmonic "levels" divided by RMS level of

RMS DEMOD spectra between 0 and 65 Hz.

Upper sb = dB level of upper slip sideband of power line peak

Lower sb = dB level of lower slip sideband of power line peak

Rotor bar health = Estimate of the percent of broken or cracked rotor bars

Thd = Total harmonic distortion

+Ve = Positive sequence harmonic

-Ve = Negative sequence harmonic

Zero = Zero sequence harmonic

Running Speed = 40.558 Hz / 2433 Rpm

Pole pass frequency = 1.343 Hz

Load = 32.0 %

Time

RMS
Peak
CF
Current 1
31.470
50.265
1.597
Current 2
30.950
50.258
1.624
Current 3
30.880
49.304
1.597
Average
31.100
49.942
1.606
% dev
1.2
1.3
1.1

Time
	RMS	Peak	CF
Current 1	31.470	50.265	1.597
Current 2	30.950	50.258	1.624
Current 3	30.880	49.304	1.597
Average	31.100	49.942	1.606
% dev	1.2	1.3	1.1

THDF = 88.1

Time

RMS
Peak
CF
Voltage 1
402.300
329.190
0.818
Voltage 2
402.400
563.440
1.400
Voltage 3
399.100
570.230
1.429
Average
401.270
487.620
1.216
% dev
0.5
32.5
32.7

Time
	RMS	Peak	CF
Voltage 1	402.300	329.190	0.818
Voltage 2	402.400	563.440	1.400
Voltage 3	399.100	570.230	1.429
Average	401.270	487.620	1.216
% dev	0.5	32.5	32.7

VDF = 99.7

App. Power
Real Power
Reac. Power

Power factor
Impedance
kVA
kW
kVARS
Phase 1
0.544
12.784
7.248
3.940
6.083
Phase 2
0.594
13.002
7.227
4.292
5.814
Phase 3
0.655
12.924
7.136
4.675
5.392
Avg/Total
0.598
12.903
21.611
12.907
17.289
% dev
9.6
0.9

	App. Power	Real Power	Reac. Power
	Power factor	Impedance	kVA	kW	kVARS
Phase 1	0.544	12.784	7.248	3.940	6.083
Phase 2	0.594	13.002	7.227	4.292	5.814
Phase 3	0.655	12.924	7.136	4.675	5.392
Avg/Total	0.598	12.903	21.611	12.907	17.289
% dev	9.6	0.9

Demand Pwr = 12.9 KW

Summary of Rotor Bar Health
Power line dB diff.
Rotor bar
Health index

Se, fund
Se, harm
Level %
Upper SB
Lower SB
Measured
1.343
1
-
-48.0
-100.0
0.0309
Severity level
Rotor Condition Assessment
Recommended Corrective Action
1
Excellent
None

Summary of Rotor Bar Health	Power line dB diff.	Rotor bar Health index
	Se, fund	Se, harm	Level %	Upper SB	Lower SB
Measured	1.343	1	-	-48.0	-100.0	0.0309
Severity level	Rotor Condition Assessment	Recommended Corrective Action
1	Excellent	None

Harmonic Distortion Results:
Voltage input, from 41.260 Hz harmonics

THD Odd %
THD Even %
+ve%
-ve %
Zero %
THD All %
Current 1
1.578
0.989
1.049
1.487
0.393
1.862
Current 2
***
***
***
***
***
28.000
Current 3
***
***
***
***
***
17.000
Voltage 1
0.087
0.182
0.056
0.033
0.191
0.202
Voltage 2
***
***
***
***
***
1.000
Voltage 3
***
***
***
***
***
1.000

Electrical Signature Analysis can detect & trend the following on Electric Motors

Bottom Line
Power Factor Commentary
Current Commentary
Voltage Commentary
Load Commentary
Phase Connection Commentary
Rotor Commentary
Stator Commentary
Rotor / Stator Air-Gap Characteristics
Harmonic Distortion Commentary
Misalignment Indications
Bearing Commentary

Harmonic distortion table
Hz	Cur1	Vlt1	Cur2	Vlt2	Cur3	Vlt3
41	29.1	0	***	***	***	***
82	0.3	0	***	***	***	***
123	0.1	0	***	***	***	***
164	0.1	0	***	***	***	***
205	0.3	0	***	***	***	***
246	0.0	0	***	***	***	***
287	0.3	0	***	***	***	***
328	0.0	0	***	***	***	***
369	0.1	0	***	***	***	***
410	0.0	0	***	***	***	***
451	0.1	0	***	***	***	***
492	0.0	0	***	***	***	***
533	0.1	0	***	***	***	***

Description

Report B (Normal motor)

Performance Summary

Bottom Line

X This motor is operating normally, no action is required.

This motor exhibits suspicious operation, trending of the motor is warranted.

This motor exhibits abnormal indications, action is warranted, NOW.

Power Factor Commentary

Power factor exceeds 0.85.

X Power factor is below 0.85, see detailed report.

Current Commentary

X Current variation is within normal limits.

Current variation is beyond normal limits, see detailed report.

Voltage Commentary

Voltage variation is within normal limits.

Voltage variation is beyond normal limits, see detailed report.

X RMS voltage differs from nameplate by more than 5%.

Load Commentary

X Load on the motor is consistent with nameplate values.

Load on the motor exceeds nameplate values, see detailed report.

Load on the motor is less than 25%.

Phase Connection Commentary

X Connections are normal.

Voltage ground reference is NOT neutral.

Loose connection.

Rotor Commentary

X Rotor bar health is normal.

Rotor bar health is questionable, see detailed report.

Load is insufficient to determine rotor bar health, at this time.


Stator Commentary

X Stator health is normal.

Stator mechanical health is questionable.

Turn to turn short.

Rotor/Stator Air-gap Characteristics

X Dynamic or static eccentricity indications do not exist.

Indications of static eccentricity exist.

Indications of dynamic eccentricity exist.

Harmonic Distortion Commentary

X There is no evidence of harmonic distortion.

There is evidence of harmonic distortion, see detailed report.

Misalignment Indications

X There are no indications of mechanical problems like misalignment or unbalance.

There are indications of mechanical problems like misalignment or unbalance.

Perform vibration survey to identify and correct the cause.

Bearing Commentary

There is no evidence of bearing problem.

X Indications of potential bearing problems, perform vibration survey to verify.

INPUT SUMMARY

NAMEPLATE INFORMATION

		Units
Manufacturer	****
Serial Number	****
Model Number	****
Motor type	Induction
Power	7.5	KW
RPM	2920	Rpm
AC/DC	AC
Poles	2
Phases:	3
Voltage	480.0	Volt
Full Load Current	13.60	Amp
Number of stator slots	-1
Number of rotor bars	-1
Torque	25	N.m
CT Ratio	1.000
PT Ratio	1.000
Duty Cycle	****
Service Factor	115
Frame Size	****
Insulation Type	****
Ambient Temperature	70.0	F°
Motor efficiency	-1.000
Power factor	0.890

Detailed Calculations

LEGENDS:

Impedance = Complex Impedance = vi/ci

CF = Crest Factor = (waveform peak)/(waveform rms)

CFC = Carrier Frequency Content = 10^(x/20)/frms, %

THDF = Transformer Harmonic De-rating Factor = sqrt(2)/CF, %

VDF = Voltage De-rating Factor = 100 - (voltage unbalance, %)^2, %

Se, fund = Location of pole pass frequency fundamental, Hz

Se, harm = Number of pole pass frequency harmonics

Level = Sum of spectral amplitudes of pole pass frequency fundamentals and

harmonics

Slip = SRSS sum of slip and harmonic "levels" divided by RMS level of

RMS DEMOD spectra between 0 and 65 Hz.

Upper sb = dB level of upper slip sideband of power line peak

Lower sb = dB level of lower slip sideband of power line peak

Rotor bar health = Estimate of the percent of broken or cracked rotor bars

Thd = Total harmonic distortion

+Ve = Positive sequence harmonic

-Ve = Negative sequence harmonic

Zero = Zero sequence harmonic

Running Speed = 49.866 Hz / 2992 Rpm

Pole pass frequency = 0.061 Hz

Load = 90.8 %

Time

RMS
Peak
CF
Current 1
13.500
22.505
1.667
Current 2
13.600
21.515
1.582
Current 3
13.800
22.123
1.603
Average
13.633
22.048
1.617
% dev
1.2
2.4
3.1

Time
	RMS	Peak	CF
Current 1	13.500	22.505	1.667
Current 2	13.600	21.515	1.582
Current 3	13.800	22.123	1.603
Average	13.633	22.048	1.617
% dev	1.2	2.4	3.1

THDF = 87.4

Time

RMS
Peak
CF
Voltage 1
401.200
336.630
0.839
Voltage 2
402.000
555.620
1.382
Voltage 3
402.700
562.830
1.398
Average
401.970
485.030
1.206
% dev
0.2
30.6
30.4

Time
	RMS	Peak	CF
Voltage 1	401.200	336.630	0.839
Voltage 2	402.000	555.620	1.382
Voltage 3	402.700	562.830	1.398
Average	401.970	485.030	1.206
% dev	0.2	30.6	30.4

VDF = 100.0

App. Power
Real Power
Reac. Power

Power factor
Impedance
kVA
kW
kVARS
Phase 1
0.829
29.719
3.125
2.590
1.749
Phase 2
0.779
29.559
3.158
2.460
1.980
Phase 3
0.799
29.181
3.206
2.560
1.930
Avg/Total
0.802
29.486
9.489
7.610
5.659
% dev
3.3
1.0

	App. Power	Real Power	Reac. Power
	Power factor	Impedance	kVA	kW	kVARS
Phase 1	0.829	29.719	3.125	2.590	1.749
Phase 2	0.779	29.559	3.158	2.460	1.980
Phase 3	0.799	29.181	3.206	2.560	1.930
Avg/Total	0.802	29.486	9.489	7.610	5.659
% dev	3.3	1.0

Demand Pwr = 7.6 KW [Load:90.8 %, Motor Eff.:90.0 %, Output Pow.:6.8 KW, Output Trq.:22 N.m]

Summary of Rotor Bar Health
Power line dB diff.
Rotor bar
Health index

Se, fund
Se, harm
Level %
Upper SB
Lower SB
Measured
0.061
1
-
-100.0
-100.0
0.0022
Severity level
Rotor Condition Assessment
Recommended Corrective Action
1
Excellent
None

Summary of Rotor Bar Health	Power line dB diff.	Rotor bar Health index
	Se, fund	Se, harm	Level %	Upper SB	Lower SB
Measured	0.061	1	-	-100.0	-100.0	0.0022
Severity level	Rotor Condition Assessment	Recommended Corrective Action
1	Excellent	None

Harmonic Distortion Results:

Voltage input, from 49.896 Hz harmonics

THD Odd %

THD Even %

+ve%

-ve %

Zero %

THD All %

Current 1

2.351

0.148

0.840

1.996

0.927

2.355

Current 2

***

***

***

***

***

5.000

Current 3

***

***

***

***

***

3.000

Voltage 1

2.083

0.055

1.376

1.526

0.345

2.083

Voltage 2

***

***

***

***

***

2.000

Voltage 3

***

***

***

***

***

2.000

Harmonic distortion table
Hz	Cur1	Vlt1	Cur2	Vlt2	Cur3	Vlt3
50	15.0	390	***	***	***	***
100	0.0	0	***	***	***	***
150	0.1	2	***	***	***	***
200	0.0	0	***	***	***	***
250	0.3	5	***	***	***	***
300	0.0	0	***	***	***	***
350	0.1	5	***	***	***	***
400	0.0	0	***	***	***	***
450	0.0	0	***	***	***	***
500	0.0	0	***	***	***	***
550	0.1	2	***	***	***	***
600	0.0	0	***	***	***	***
650	0.0	0	***	***	***	***

Description:

Harmonic Distortion Results: Voltage input, from 41.260 Hz harmonics
	THD Odd %	THD Even %	+ve%	-ve %	Zero %	THD All %
Current 1	1.578	0.989	1.049	1.487	0.393	1.862
Current 2	***	***	***	***	***	28.000
Current 3	***	***	***	***	***	17.000
Voltage 1	0.087	0.182	0.056	0.033	0.191	0.202
Voltage 2	***	***	***	***	***	1.000
Voltage 3	***	***	***	***	***	1.000