The document discusses electric and magnetic fields produced by conductors and their effects on human health. It summarizes research showing fields can induce tiny currents in the body, but the health effects of long-term exposure are still unclear. Guidelines from ICNIRP limit field exposure and were used to survey fields in DEWA substations, finding all levels were under restricted limits and pose no health risks.

1. Field Effects over Human Health & Guidelines
Pankaj Singh

2. Electric & Magnetic Field
 Electric Field- The voltage on any current carrying
conductor or electrically charged surface produces
electric field around it. The electric field strength is
measured in volts/meter or KV/m.
 Magnetic fields- The current carrying conductors
produce magnetic field around it. Magnetic fields are
measured in Tesla or µT.

3. Effects of field exposure on human health
 Different researches have been conducted to identify the effects of
fields on neurobehavioral, neurodegenerative disorders, cancer, &
cardiovascular disorders on human body. However all the disorders
are not yet been scientifically proven to have any clear relation with
the fields.
 ICNIRP (International Commission on Non- Ionizing Radiation
Protection) is an international scientific body and is recognized by
WHO (world health organization). ICNIRP has reviewed the
research and studies of field exposure on the human health.
 ICNIRP concluded that there are clear evidence that many tinny
currents are induced in the human body due to electric and
magnetic fields exposure. These currents can interface with body’s
nervous system as human body has well defined biological
responses to low frequency fields

4. Central Nervous System
 CNS- Nervous system is the essential part of the
body which transmits various signals across the
various parts of the body or its releases
messages back & forth from the brain to
different parts of the body. It also helps in the
coordination of voluntary and involuntary
actions of the body. At the cellular level the
nervous system is consists of a special type of
cell called neuron or nerve cell. Neurons are
connected to each other to transmit signals to
form the nervous system. Neurons have special
structure that allow them to send signals
rapidly and precisely using a common pathway
for the passage of electrical pulses. Neurons are
responsive in nature which means neurons
respond to feelings and communicate the
presence of the feeling to central nervous
system which in turn is processed and send to
other parts of the body for action.

5. CNS Disorders Due To Fields
 Neuro-degenative disorder-it is the umbrella term for the
progressive loss of structure or function of neuron, including
death of neurons. This means that neuron cells start to decay
and die. Which gives rise to many diseases including brain
tumor.
 Neurobehavioral disorder- Cognitive, behavioral, and emotional
disorders associated with damage or dysfunction in the CNS. A
slowly progressive deterioration in intellectual and adaptive
functions, disorders in carrying out learning complex moments,
poor judgment, uninhibited social behaviors, crude language &
humor, impulsive nature etc.
 Cardiovascular disorders- diseases related to heart of blood
vessels.

6. Some specific Effects of field exposure
on human health
 Electrical fields above the threshold of the retina phosphenes can
interact with the ongoing rhythmic electric activity in visual & motor
cortices and slightly affect the visual processing. As the effect of which
we may see the illusion of light, flickering lights or any such
disturbance in visuals.
 Stronger fields affect the muscles tissues which can cause discomfort
then pain.
 Human nerve tissues can be stimulated by fields which may cause
multiple effects like annoyance and irritation. Since the nerve tissues of
central nerves system and cardiac muscle tissues can equally be
stimulated by fields so they need special attention as they can be life
threatening.
 All low frequency electric fields can be detected by animals, most likely
as a result of surface charge effects and may elicit transient arousal or
mild stress.

7. Field Exposure Guidelines by ICNIRP
ICNIRP has issued
guidelines regarding the
exposure limits
considering only the
scientifically established
effects on the health.
These guidelines set a
basic restriction of
current density in human
body. Since the induced
current density in human
body is difficult to
measure they have set
reference levels for
exposure. ICNIRP has set
different levels for
occupational and general
public exposure.

8. Electric & Magnetic field Inspection in DEWA
substations
We conducted a survey of
exposed electric and
magnetic fields in the
DEWA substation.
Transformers are prime
source of electric and
magnetic fields so data has
been recorded in 33 KV &
11/6.6 KV substations as
below layout. The five test
points has been identified
as indicated in the above
figure for measurement.
Test points 1 to 4 are on
four side’s transformer,
from HV terminal to LV
terminal in anticlockwise
direction. The fifth test
point is just outside the
transformer room

9. Data Analysis
 Data is collected by measuring the exposed electric and
magnetic fields at test points as described above. In primary
substations up to 85% of the transformers have been included in
the survey so results can be easily projected on the whole
population.
 In secondary substations random samples survey has been
conducted with a confidence level 95 % and confidence interval
17. Since the population in secondary substations is identical in
nature the confidence interval can be assumed to be between 10
to 13. From the survey it can be observed that electric field is
almost constant over different manufacturers and load profiles.
Magnetic field being directly proportional to current has
different values around the unit.

10. Primary Substation
 Electric field- The
summery of electric field
survey in primary
substations is as below.
Survey has been
conducted for 61 samples.
As per table maximum
field is observed in HV
winding area. From the
below trend of the electric
field we see that electric
field is almost constant
over the different load
profiles and
manufacturers. The
recorded values lie well
within the prescribes
exposure limits.

11. Electric field exposure on primary
sudations

12. Magnetic Field
 The summery of the
magnetic field survey in
primary substations is in
below tables. The
maximum intensity of
magnetic fields is
observed in the LV
terminal area. From the
scatter graph below, we
see that magnetic field
increases with increase
in load, however all
points lie we within the
specified limits.

13. Exposed Magnetic Field in primary substations
0
2
4
6
8
10
12
14
16
0 0.5 1 1.5 2 2.5 3 3.5 4
MagneticFieldµT
Load MW
Magnetic
filed at LV
Terminal

14. Secondary substation
 Electric field – The
summery of electric
field survey in
secondary
substations is in
below table. The
electric field has got
very marginal
variation and is well
within the limits,
over the different
load profiles and
manufacturers. The
same can be verified
by the trend of the
field variation.

15. Exposed Electric Field in secondary substations
0
1
2
3
4
5
6
7
0 50 100 150 200 250 300 350
ElectricFieldV/M
Load Amps
Electric Field

16. Magnetic field –
 Magnetic field –
The summery table
of magnetic field
survey in secondary
substations is as
below. Maximum
values of magnetic
fields are recorded
on the LV terminal
sides of units. The
magnetic fields vary
proportional to load
as indicated by the
trend. The recorded
values lie within the
limits.

17. Exposed Magnetic Field secondary substations
0
5
10
15
20
25
0 50 100 150 200 250 300 350
MagneticFieldµT
Load Amps.
Magnetic
Field On LV

18. Conclusion
 The data collected on exposed field clearly indicates
that the level of exposed fields is under the restricted
limits of ICNIRP and pose no health related threats
either to general public or occupational. As per our
current level of knowledge according to researches and
studies there is no need to have expensive measures of
protection for preventing the exposed electric &
magnetic fields, however we should try to protect
ourselves from exposing to high fields as far as
possible.