Zigzag transformer ZN (ZIGZAG), ZNYN, YND(OPEN), Li0, Grounding Earthing transformer
Key attributes
Usage:Power Distribution
Phase:Three
Coil Structure:TOROIDAL
Coil Number:Two windings
Place of Origin:China
Model Number:Safe
Product name:Grounding transformer
Type:Oil/dry
Frequency:50/60Hz
Standard:IEC60076
Cooling Method:ONAN
Vector group:ZIGZAG
Certification:ROHS
Application:Power Distribution System
Warranty:2 Years
Function:Earthing protection
Overview
GROUNDING TRANSFORMERS/EARTHING TRANSFORMERS
[ZN (ZIGZAG), ZNYN, YND(OPEN), Ii0]
Grounding Transformers are designed to provide an artificial, neutral point for ungrounded three phase power systems.
During the line-to-ground faults, grounding transformers provide an easy path to ground faults, thus limit the fault currents and transient over-voltages.
Grounding transformers normally carry short-circuit ground current until the circuit breaker clears the fault. Therefore, they have short time ratings.
The kVA rating of a earthing transformer depends on the normal line-to-neutral voltage and the fault current value for a specified time, such as seconds to minutes.
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Test List
Visual & Dimensional Check
Measurement of Voltage Ratio
Measurement of Winding Resistance
Measurement of Zero Sequence Impedance
Measurement of No-Load Loss and Current
Measurement of Short-Circuit Impedance and Load Loss
Dielectric Tests
Separate Source AC Withstand Voltage Test
Induced AC Withstand Voltage Test
Lightning Impulse Test
Temperature Rise Test
Final Check
For special tests, please contact us.
Please take a brief moment and use the “Check List” below to gather the following (13) basic pieces of Grounding Transformer information:
- Winding configuration; either Zig Zag or Two Winding.
- Voltage(s) and BIL; The line-to-line value of the system to which the grounding transformer is to be connected. If a two winding grounding transformer is required, the secondary voltage must be provided as well.
- Continuous neutral current.
- System available neutral fault current and duration; example 500 amps for 10 seconds, 4000 amps for 2 seconds.
- Zero Sequence impedance percentage.
- Per phase impedance in Ohms.
- Per phase resistance in Ohms.
- X/R ratio; typically a value > 4.0.
- Special application conditions; i.e. 2000 MASL, etc.
- Enclosure construction or NEMA designation preference; i.e. high security compartmentalized padmounted, standard ventilated or substation design, special paint color, etc.
- Terminal connectivity preference; i.e. dead front, live front, conventional terminals, etc.
- Winding material; CU if not specified.
- Transformer temperature rise; 150° C if not specified.
Design Concept of our Transformer
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Our transformers are designed and manufactured through verification from the design stage using design program, electromagnetic field analysis program, and structural analysis program
- Dielectric Strength
| Our transformers guarantee dielectric strength to withstand impulse voltage thanks to high-technology design which ensures low capacitance between winding and the ground and proper coordination of insulating material and solves creepage problem. |  |
- Thermal Capability
| Heat generated from coils which form electric circuit inside the transformer and heat from iron cores form magnetic circuit and is transmitted to insulating oil. Heat transmitted to insulating oil radiates to the air through the cooler. Cooling effect is very important as it is directly linked to insulation life and the capacity of the transformer. Our transformers lay emphasis on improving cooling performance and regulating temperature of the hottest spots by using an effective cooling system. |  |
- Mechanical Strength
| Reliability of transformers manufactured by us is excellent because of winding and tank design which distributes mechanical force evenly in case of short circuit and supports short-circuit strength effectively. |  |
Manufacture Procedure
01 Windings
Windings are composed of two parts, namely, a conductor and insulation material. For the conductor, we use high grade electrolytic copper or aluminium. Our Oil Immersed Transformers obtain high thermal capacity with the use of Epoxy coated Insuldur Kraft Paper, which has higher short time overload capacity than any other Kraft paper type.
02 Core
Core design is essential because it determines the transformer’s efficiency and noise level. For high dimensional accuracy, the core cutting processing of us is controlled by a computerized system. By Step-Lap core stacking, Our Oil Immersed Transformers attain to optimal characteristics for each customer.
03 Winding Support System
Coils are sized and clamped by being pressed with a special hydraulic fixture after assembly with the core. With Axial and Radial direction, we reinforce the winding support system. This secure structure helps withstand harsh short circuit forces.
04 Radiator
The transformer will be furnished with panel or corrugated radiators assuring that the temperature rise of the windings or oil will not exceed their specified limit when the transformer continuously operates at the rated full load.
Glances in workshops:
Product packing:
