Electric Energy T&D - Index

Electric Energy T&D - EE Magazine March / April - Index

Through its Energy Automations Solutions
group, it is also a leading provider of
software, communications and integration
solutions that enable customers to increase
productivity, improve system reliability, and
reduce costs. For more information, go to
www.cooperpower.com, www.cannontech.com
or www.cybectec.com.
circle 58 on Reader Service card
_______________________________________
Step and Touch Potential Gets
Grounded
By Lewis Shaw
For those in the lineman profession every day
has the potential to bring the unexpected.
Lineman must always think safety first, and
be diligent when performing even the most
routine tasks. However, even with such
precautionary measures, it’s hard to protect
against unknown hazards.
Every year dozens of lineman are either injured
or killed due to unfortunate circumstances
involving high voltage mishaps. According to
the Safety Fireman’s Archive, in 00 alone
more than 50 linemen in the United States
were killed while on the job. A preconceived
notion in the industry is that you are safe if
the line is tagged and there are grounds on
both sides of the work area. However, that is
not always the case.
Over the years lineman have become quite
proficient in creating an equal potential
zone at the pole top, however their still
remains hazards on the ground that are often
overlooked. These can be defined as, “step”
or “step and touch” potential. On a pole or in
a bucket, we can create and control the equal
potential zone. On the ground the voltage
becomes difficult to control. The danger
becomes the difference in voltage between
the workers feet, should they bridge too
large a gap. The second danger becomes the
difference in voltage between the workers feet
and his hand, should they touch an energized
object. For example; when operating an uninsulated
gang operated switch from ground
level, if the switch fails, a line can drop onto
the base of the switch. The entire switch,
including the handle being used by the
worker, would then be energized at full line
potential. OSHA has addressed this hazard in
the Equi-Potential Zone requirement.
The Occupational Safety and Health Administration
(OSHA) requirement 1910. 69 states
“Equi-Potential Zone: temporary protective
grounds shall be placed at such locations and
arranged in such a manner as to prevent each
employee from being exposed to hazardous
differences in electrical potential.”
Compliance with the OSHA regulation can be
achieved three ways. One option is the use of
a Portable Protective Ground Mat. This item
offers a means to create an equal potential
zone at ground level. The second option is
OSHA suggests, is to insulate the worker with
equipment such as rubber gloves, or as the
third option, preventing access to areas where
the hazardous voltages exist. The ultimate
goal is to protect the worker from contact.
According to Dick Cole at Hastings, the use
of a portable mat for activities like switching
processes, splicing cables in trenches,
making cable terminations on transformers,
opening or closing overhead air breaks, and
working on control boxes offers a new level
of protection and safety. We had a customer
situation not to long ago where the mats were
being used at a site where the switchman was
performing a routine switching procedure.
While performing their duties an incident
occurred that had sufficient voltage and
current to burn several portions of the mat
stitching yet the worker remained unharmed.
The internal braid grid and the larger external
perimeter braid remained intact. This extra
piece of equipment saved the workers life.
6 I March-April 2008 Issue
For more information regarding this topic
please visit:
http://www.cdc.gov/niosh/88-104.html
http://www.osha.gov
http://www.hfgpgrounding.com
circle 59 on Reader Service card
_______________________________________
Early Findings from 2008 Newton-
Evans Study of Electric Power
Control Center Officials Indicate
Significant Activities Underway to
Develop “Smart Grid” Components
and Strengthen Security Measures.
Early findings from the ongoing 008 study
of mission critical, real-time electric utility
systems including energy management,
supervisory control, and distribution network
management include the following:
Communications Protocols:
Despite marketing pressures from global
equipment suppliers, the vast majority of
North American utilities reporting in to date
are not likely to adopt the IEC 61850 protocol
beyond experimental testing during the time
horizon of this new study. Officials are
satisfied with their current communications
protocols, led by DNP 3 (both serial and LAN
versions) and are using TCP/IP to a greater
extent than found in earlier studies.
Smart Grid Activities Underway:
When asked about plans concerning which
aspects of an intelligent or smart grid program
are being highlighted during 008- 010,
officials are indicating two “hot” areas for
investment at this time. These are: advanced
metering infrastructure and distribution
network automation, including fault detection,
isolation and service restoration.