No Date Organisation Comment MCA Consideration

rewardreminiscentElectronics - Devices

Nov 24, 2013 (3 years and 10 months ago)

72 views

Potential Hazards of Excessive Harmonic Distortion of Cur
rent and Voltage of Onboard Electrical Systems

Consultation comments summary

No

Date

Organisation

Comment

MCA Consideration

1

05.03.2012

Fred Hardy

UK Marine CE

BV

The document refers to IEEE standards but the most of
classification societies refer to IEC 60092
-
501 (Electric
Propulsion Plant) where THD limits are a little differen
t:

For the propulsion network the total harmonic disortion
(THD) value of the voltage shall not exceed 10%. If a
THD
-
value of 10% is exceeded, the person responsible for
the propulsion system, see 4.2, shall ensure interference
-
free operation of all conne
cted equipment. If the
propulsion network and the ship’s network are directly
connected the THD value of the voltage shall not exceed
the values stated in IEC 60092
-
101”

Reference included

2

15.03.2012

Dario Bruni

RINA

No Comments

N/A

3

12.03.2012

John V
anezos

IACS

Following items are to be supplemented in the “8.
Glossary and definitions”




Total Harmonic Distortion (THD) : The ratio of the
r.m.s value of the residue, after elimination of the
fundamental, to the r.m.s value of the fundamental
expressed i
n percent. (Quoted from IEC 60092
-
101,
1.3.24.2)




Single harmonic : the single harmonic content of a
voltage wave is the ratio of the effective r.m.s value
of that harmonic to the r.m.s value of the
fundamental expressed in percent. (Quoted from
IEC 60092
-
101, 1.3.24.2)







Included






Included








Potential Hazards of Excessive Harmonic Distortion of Cur
rent and Voltage of Onboard Electrical Systems

Consultation comments summary

The following reference documents are to be added:




IEC 60092
-
101, Electrical installation in ships


Part
101 : Definitions and general requirements




IEC 60092
-
501, Electrical installation in ships


Part
501 : Special features


Electri
c propulsion plant




IEEE Std. 45
-
2002, Table 4 : Alternating current
(ac) Power Characteristics




IEEE Std. 519
-
1992, Recommended Practices and
Requirements for Harmonic Control in Electrical
Power Systems


In addition we have the following observation:


A
high
-
capacity condenser has a shorter usage life than a
normal capacity one. Therefore, the condition of a high
-
capacity condenser needs to be carefully monitored and
the condenser should be replaced regularly as needed. As
the THD problems are quite serio
us the maintenance
management of a high
-
capacity condenser may be an
issue.

Included




Included



Included



Included




Noted, but not
included

4

14.03.2012

Kristine Dehn

DNV

The second bullet point in the summary reads
:


If left unchecked, harmonic distortion can greatly shorten
the life of electronic equipment and cause damage to
power systems, which could potentially result in fire.








Potential Hazards of Excessive Harmonic Distortion of Cur
rent and Voltage of Onboard Electrical Systems

Consultation comments summary

We assume that “electric equipment” is a better wording,
as motors, transformers and
generators are affected by
the THD as well


The last bullet point in clause 6.1 states: Installing
generators with a large sub
-
transient reactance.


We assume that the correct wording should be “generators
with a low sub
-
transient reactance”, since a low
reactance
will result in less distortion of the terminal voltage.


Change accepted






Change accepted

5

16.03.2012

Jan van der
Schans

ABS Europe

The word “generators” replaced by “machine” in the
summary.


Introduction edited to read “capacitor
in a harmonic filter.
The”


No 1 amended to include “variable voltage fed by variable
speed drives. The power electronic devices used in these
variable speed drives”


Page 2, various amendments including re
-
formatting and
replacing of words have been sugg
ested.


Page 3, 3
rd

bullet point now reads “which reduces a
cable’s effective current
-
carrying cross sectional area. An
additional bullet point has been added “Greater than
normal earth leakage current detection as a result of
common mode voltages


Page 4
, various amendments suggested including
reformatting and minor text changes

Accepted



Accepted



Text amended
accordingly



Changes accepted



Changes accepted






Changes accepted

Potential Hazards of Excessive Harmonic Distortion of Cur
rent and Voltage of Onboard Electrical Systems

Consultation comments summary