Basic transformer harmonics are discussed in this presentation.

1. Acme Electric
Transformer Seminar
K - FACTOR TRANSFORMERS
HARMONIC MITIGATING TRANSFORMERS
I-TRAP NEUTRAL CURRENT REDUCER

2. WHAT ARE HARMONICS ?
A sinusoidal waveform with a frequency that is
an integral multiple of the fundamental
frequency.
60hz Fundamental
120hz 2nd Harmonic
180hz 3rd Harmonic
240hz 4th Harmonic
etc...
Note: Each individual harmonic is sinusoidal.

3. 0
360
FUNDAMENTAL (60Hz) & 5TH
HARMONIC (300Hz)

4. SUM OF 60Hz & 300Hz
(FUNDAMENTAL & 5TH HARMONIC)
0
360

5. WHERE DO HARMONICS
ORIGINATE?
Harmonics primarily originate in electronic
power converters.
These can be found in:
1. Switch Mode Power Supplies
2. Electronic Ballasts
3. Variable Frequency Drives
4. Oven and Furnace Controls
5. Rectifier Circuits

6. PROBLEMS CREATED BY
HARMONIC CURRENTS
1. OVERHEATED Neutrals
2. OVERHEATED Transformers
3. Malfunctioning of Equipment due to
excessive voltage distortion
4. BURNED-OUT Motors
5. Tripped Circuit Breakers
6. Blown Fuses

7. TRIPLEN HARMONICS
Triplen harmonics include the 3rd harmonic and
all the odd multiples of the 3rd.
Example: 3rd, 9th, 15th, 21st, 27th, 33rd, etc
Note: Triplen harmonics tend to add up in the three phase neutral
conductor.

8. TYPICAL 208Y/120 SYSTEM

9. EFFECTS ON HARMONICS ON
TRANSFORMERS
1. INCREASED TEMPERATURE RISE
2. INCREASED NEUTRAL CURRENT FLOW
3. INCREASED CORE LOSSES
4. Increased sound level
5. Decreased efficiency

10. K - FACTOR
• A measure of a transformer’s ability to
withstand the heating effects of non-
sinusoidal harmonic currents created by
much of today’s electronic equipment.
• The stray losses of the transformer are
multiplied by the K-Factor of the load
resulting in increased heating of the unit.

11. TRANSFORMER CONDUCTOR
LOSSES
• Transformer conductor losses are composed
of AC and DC losses.
• AC losses = stray losses
• DC losses = I^2 x R
• Total conductor losses = AC + DC losses
Note: Stray losses get multiplied by the K-factor of the load.

12. EXAMPLE OF TEMPERATURE
RISE TYPICAL 75 KVA TP1
EXAMPLE:
75 kVA, 3-Ph, 480 - 208Y/120, 150 degree rise
Total conductor losses at K-1 (linear load) =
2860W + 135W = 2995W
Rise @ K-1 = 150 degrees C
If K=20 (non-linear load), new conductor losses
are:
2860 + (20 x 135) = 5560 watts
Rise @ K-20 = 244 degrees C

13. THREE SOLUTIONS TO
HARMONIC PROBLEMS
1. K - Rated Transformers (traditional)
2. Harmonic Mitigating Transformers (zig-zag)
3. I-Trap Neutral Current Reducer

14. K - RATED TRANSFORMERS
• K - Rated or Non-Linear transformers do not
eliminate harmonics!
• They are only designed to tolerate the
heating effects of harmonics created by much
of today's electronic equipment.

15. K-RATED (CONTINUED)
K-rated transformers are traditional Delta-Wye
transformers
• They are designed with lower flux densities
and no load losses as well as lower I²R
losses resulting in a larger and heavier unit.
• They do not eliminate or cancel harmonics

16. K-FACTOR FEATURES
• Available in K-Factors of 4, 13, and 20
• Aluminum or Copper windings.
• Available temperature rises of 150, 115, or 80
• UL listed and CSA certified

17. K-FACTOR AND DOE 2016
• As of January 1, 2016 K-Rated transformers
must comply to the efficiency standards
(DOE 2016) of the National Energy Bill
• They are only required to comply with a
connected load condition of K1 (no
harmonics)

18. HARMONIC MITIGATING
TRANSFORMERS
• They consist of a Delta primary and a Zig-
Zag secondary.
• The Zig-Zag secondary causes a phase shift
in the triplen harmonics which results in a
canceling effect. This prevents the triplen
harmonic losses from being coupled back
into the primary and results in cooler
operation and increased energy efficiency.

19. WHAT IS A ZIG-ZAG WINDING?
• The secondary winding on each magnetic leg
of the core is wound in two separate sections.
These sections are then transposed between
different legs of the core to create the Zig-
Zag secondary.
• Each 120V output of the transformer consists
of two sections from different magnetic legs
resulting in a magnetic phase shift.

20. DIAGRAM SHOWING DELTA
PRIMARY AND ZIG-ZAG SECONDARY
( ZERO DEGREE ANGULAR DISPLACEMENT)
X0

21. HARMONIC MITIGATING BENEFITS
1. Unlike K-Rated transformers, Harmonic
Mitigating transformers actually treat the triplen
harmonics in the Zig-Zag secondary winding
2. Reduce supply voltage flat topping caused by
non-linear loads
3. Improve overall power factor of supply system
4. Suitable for K-Factor loads
5. Improved energy efficiency (Meet DOE 2016 at
K-1 load)

22. MITIGATING TRANSFORMER
FEATURES
• Copper foil conductor to minimize “skin effect”
of harmonic currents
• Taps: 2 x 2.5% ANFC and BNFC
• 220 Degree C insulation system with 150
Degree C rise
• UL listed and CSA certified
• Zero degree angular displacement between
Primary and Secondary windings

23. IMPORTANT POINTS TO REMEMBER
• Harmonic mitigating transformers don’t treat
harmonics or neutral current until they reach the
transformer windings
• Transformer has 200% Neutral Bar
• Neutral conductor from transformer to Load
Panel should be sized at 200%

24. ACME ADVANTAGES
1. Acme utilizes special winding techniques and
“foil” conductors in both its K-Factor and
Harmonic Mitigating transformers to minimize
the heating effects of harmonic currents. (Skin
effect)
2. The use of foil conductor increases the
dielectric strength of the insulation because one
layer is only one turn. Foil also eliminates the
effects of axial forces which can result in failure
of wire wound transformers.

25. SKIN EFFECT ILLUSTRATED
Round or rectangular magnet
wire
= =
60
Hz
Higher
Hz
Foil conductor is very thin and much wider
Minimizes skin effect at higher Hz
No current flow in center of conductor - Skin
effect
Thinner but wider conductor
Full current flow

26. APPLICATIONS
• Hospitals and Health Care Facilities
• Commercial & Educational Facilities
• Airport Facilities
• Telecom Facilities
• Broadcasting Facilities
• Internet Service Providers
• Data Centers

27. I-TRAP NEUTRAL
CURRENT REDUCER
Technical Description:
• Low impedance - Zero sequence
• Auto Zig-Zag transformer

28. I-TRAP APPLICATIONS
1. It is used to reduce excessive current flow in
the neutral of a 3 phase 208Y/120 volt system.
2. It is available in ampere ratings of 100, 150,
300, and 450. It includes a front mounted amp
meter for monitoring neutral current.
3. Target areas: Data processing centers,
Hospitals, Radio and TV stations, Large
computer labs, etc. (Any area having numerous
electronic 120V loads powered from a
208Y/120 system)

29. HOW DOES THE I-TRAP WORK?
• Third harmonic currents are “in-phase” (additive) in
the three phase neutral.
• The low impedance and auto Zig-Zag characteristics
of
the I-Trap target the third harmonic currents causing
them to become “out of phase” in the three phase
neutral, resulting in a canceling effect. Reductions of
50% to 90% are typical.
• In many applications, the Acme I-Trap provides an
easier and more affordable solution than replacing
existing Neutral conductors.

30. I - TRAP PERFORMANCE
Reduction in Phase Current:
Before After
Phase A 49.4 42.9
Phase B 39.2 40.1
Phase C 63.2 53.6
Average 50.6 45.5
Max phase amps reduced from 63.2 to 53.6 (18%)
Phase unbalance reduced: Before-62% ; After–
34%

31. PERFORMANCE DATA
Phase A B C
I-Trap Out In Out In Out In
RMS 49.4 42.9 39.2 40.1 63.2 53.6
1H 39.0 40.0 31.0 38.0 51.0 50.0
3H 27.0 1.0 21.0 3.0 34.0 10.0
5H 13.0 15.0 11.0 13.0 15.0 16.0
7H 4.0 4.0 4.0 5.0 3.0 4.0
9H 1.0 --- 1.0 1.0 1.0 1.2
11H 1.0 --- 1.0 --- 1.0 ---
Har. Dist. 78.2% 37.7%77.6% 39.0% 73.2% 38.0%
K – Factor 5.5 4.4 5.8 4.3 4.8
3.8

32. REDUCTION IN NEUTRAL CURRENT
I - Trap Out In
RMS 84.8 8.1
1H 17.0 1.0
3H 83.0 8.0
5H 3.0 ---
7H 2.0 ---
9H 1.0 ---
11H 1.0 ---

33. QUESTIONS?