Sola/Hevi-Duty K-Factor Transformers


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Home > Products > Transformers > Distribution > K-Factor

K-Factor Transformers

K-Factor transformers are designed to reduce the heating effects of harmonic currents created by loads like those shown in Chart A (below). The K-Factor rating is an index of the transformer's ability to withstand harmonic content while operating within the temperature limits of its insulating system. Hevi-Duty K-Factor transformers have UL ratings of K-4, K-13 and K-20.

The Hevi-Duty K-Factor design is a specialized transformer that offers these benefits:

Conductors capable of carrying the harmonic currents of non-linear loads without exceeding the temperature rating of the insulation system.
A transformer design that takes into account the increase in naturally occurring "stray" losses caused by non-linear loads. These losses cause standard transformers to dramatically overheat and substantially shorten design life.
A core and coil design that manages the DC flux caused by triplen harmonics*. As these harmonics increase, they cause additional current to circulate in the delta winding. This produces a DC flux in the core which leads to core saturation, voltage instability and overheating.

* Triplen harmonics are those harmonics which are odd multiples of third harmonic (9th, 15th, 21st, etc.

On this page: Features, Accessories and Optional Design Styles, Typical Load K-Factors, Selection Tables

Features

Conductors to carry harmonics of a K-rated load without exceeding insulation temperature ratings
UL 1561 listed up to K-20 rated protection
Rated temperature rise of 150°C, 220°C insulation
Shielded for quality power
Basic design takes "stray losses" into account and functions within safe operating temperatures
Core and coil design engineered to manage the zero sequence flox caused by triplen harmonics
Provides 100% rated current without overheating the windings or saturating the core

Accessories and Optional Design Styles*

Wall mounting brackets (500 lbs maximum)
Weather Shields (UL-3R)
Totally enclosed non-ventilated designs
Low temperature rise units available
Open core and coil designs
Copper Wound designs

*Not all optional designs are UL Listed. Contact Technical Service.

Chart A: Typical Load K-Factors*

Load	K-Factor
Electric discharge lighting	K-4
UPS with optional input filtering	K-4
Welders	K-4
Induction heating equipment	K-4
PLCs and solid state controls (other than variable speed drives)	K-4
Telecommunications equipment (e.g. PBX)	K-13
UPS without input filtering	K-13
Multiwire receptacle circuits in general care areas of health care facilities and classrooms of schools, etc.	K-13
Multiwire receptacle circuits supplying inspection or testing equipment on an assembly or production line	K-13
Mainframe computer loads	K-20
Solid state motor drives (variable speed drives)	K-20
Multiwire receptacle circuits in critical care areas and operating/recovery rooms of hospitals	K-20
Reprinted with permission from EDI Magazine*

Three Phase Selection Tables

Group A: K-4 Rated 480 ∆ Primary, 208/120 Secondary, 60 Hz

UL File:

kVA	Catalog Number	NEMA 3R Weather Shield*	Height (inch)	Width (inch)	Depth (inch)	Ship Weight Approx. (lbs)	Design Style**	Elec Conn	Prim. Amps	Sec. Amps
15	3H4T2H15S	WS-02	23	18	14	180	1	2	18.1	41.7
30	3H4T2H30S	WS-14	28	23	16	329	1	2	36.1	83.4
45	3H4T2H45S	WS-14	28	23	16	357	1	2	54.2	125
75	3H4T2H75S	WS-30	34	28	22	647	1	2	90.3	208
112.5	3H4T2H112S	WS-10	44	33	21	890	1	2	135	313
150	3H4T2H150S	WS-10	44	33	21	1045	1	2	181	417
225	3H4T2H225S	WS-11	46	36	24	1230	1	2	271	625
300	3H4T2H300S	WS-11	46	36	24	1420	1	2	361	834
500	3H4T2H500S	WS-12	65	45	35	2460	1	2	602	1390
Weather shields come in a set of two and need to be ordered separately. *Design Style and Electrical Connections can be found by clicking the link or by selecting the pdf files to the left.

Group B: K-13 Rated 480 ∆ Primary, 208/120 Secondary, 60 Hz

UL File:

kVA	Catalog Number	NEMA 3R Weather Shield*	Height (inch)	Width (inch)	Depth (inch)	Ship Weight Approx. (lbs)	Design Style**	Elec Conn	Prim. Amps	Sec. Amps
15	3H13T2H15S	WS-14	28	23	16	305	1	2	18.1	41.7
30	3H13T2H30S	WS-30	34	28	22	405	1	2	36.1	83.4
45	3H13T2H45S	WS-30	34	28	22	535	1	2	54.2	125
75	3H13T2H75S	WS-30	34	28	22	805	1	2	90.3	208
112.5	3H13T2H112S	WS-10	44	33	21	972	1	2	135	313
150	3H13T2H150S	WS-11	46	36	24	1325	1	2	181	417
225	3H13T2H225S	WS-11	46	36	24	1515	1	2	271	625
300	3H13T2H300S	WS-12	65	46	35	2460	1	2	361	834
Weather shields come in a set of two and need to be ordered separately. *Design Style and Electrical Connections can be found by clicking the link or by selecting the pdf files to the left.

Group C: K-20 Rated 480 ∆ Primary, 208/120 Secondary, 60 Hz

UL File:

kVA	Catalog Number	NEMA 3R Weather Shield*	Height (inch)	Width (inch)	Depth (inch)	Ship Weight Approx. (lbs)	Design Style**	Elec Conn	Prim. Amps	Sec. Amps
15	3H20T2H15S	WS-14	28	23	16	305	1	2	18.1	41.7
30	3H20T2H30S	WS-30	34	28	22	405	1	2	36.1	83.4
45	3H20T2H45S	WS-30	34	28	22	535	1	2	54.2	125
75	3H20T2H75S	WS-30	34	28	22	805	1	2	90.3	208
112.5	3H20T2H112S	WS-10	44	33	21	972	1	2	135	313
150	3H20T2H150S	WS-11	46	36	24	1325	1	2	181	417
225	3H20T2H225S	WS-11	46	36	24	1515	1	2	271	625
300	3H20T2H300S	WS-12	65	45	35	2460	1	2	361	834
Weather shields come in a set of two and need to be ordered separately. *Design Style and Electrical Connections can be found on page

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