200kVA 33/0.4kv Grounding Earthing Transformer Auxiliary Transformer

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200kVA 33/0.4kv Grounding Earthing Transformer Auxiliary Transformer

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Product Description

A grounding transformer or earthing transformer is a type of auxiliary transformer used in three-phase electric power systems to provide a ground path to either an ungrounded wye or a delta-connected system. Grounding transformers are part of an earthing system of the network. They let three-phase (delta connected) systems accommodate phase-to-neutral loads by providing a return path for current to a neutral.

Grounding transformers are typically used to:

Provide a relatively low-impedance path to ground, thereby maintaining the system neutral at or near ground potential.
Limit the magnitude of transient overvoltages when restriking ground faults occur.
Provide a source of ground fault current during line-to-ground faults.
Permit the connection of phase-to-neutral loads when desired.

Grounding transformers most commonly incorporate a single winding transformer with a zigzag winding configuration, but may also be created with a wye-delta winding transformer. Neutral grounding transformers are very common on generators in power plants and wind farms. Neutral grounding transformers are sometimes applied on high-voltage (sub-transmission) systems, such as at 33 kV, where the circuit would otherwise not have a ground; for example, if a system is fed by a delta-connected transformer. The grounding point of the transformer may be connected through a resistor or arc suppression coil to limit the fault current on the system in the event of a line-to-ground fault.

Features

High reliability, advanced level of performance, economic indicators and reasonable.
Using phase-shaped core of three joints, curing paint brushing the surface to reduce wear and tear and noise.
Winding structure of a new oil road design is reasonable, with the new insulation to improve the mechanical strength and the ability to engage in short-circuit.
Tank forms, beautiful, generous.

Range of application

It can be widely used in urban power network as well as petrochemical, metallurgical, textile and humid, inaccessible enterprises, and mining.

Product Parameters

33/0.4KV EARTHING TRANSFORMER
Parameter	Unit	Required
Manufacturer	-	-
Type	-	Outdoor, oil immersed, self-cooled, hermetically sealed and core type
Dielectric Type	-	Mineral Oil (NOT Askarel nor PCBs)
Standards	-	IEC 60076/60354
Cooling system	-	ONAN
Vector Group	-	ZNyn11
Protection class	-	IP55
Insulation class	-	A
Size (Length x Width x Height)	mm	-
Rated Power	kVA	200
Efficiency at full load and 100% p.f	%	98
No load current	%	5.5
Rated Primary Voltage	kV	33
Rated Secondary Voltage	kV	0.4
Nominal Frequency	Hz	50
Number of phases	-	3
Off-load tap changer	-	±2 x 2.5%
Number of taps	-	5
Rated short circuit power	kA	25
Short circuit current (permanent)	kA	0.078
Permissible neutral current for 5sec	A	4200
Zero sequence Current: DB	A	160
Zero sequence Current: KB 5sec	A	1050
Zero sequence impedance	Ohm/phase	10
Test Voltages
Power frequency withstand/Induced voltage test: -High voltage winding at 200Hz	kV	70
Separate source voltage test: -High voltage winding at 60 sec -Low Voltage winding at 60 sec -Neutral winding at 60 sec	kV kV kV	70 - -
Impulse withstand test voltage full wave 1.2/50micro sec. -High voltage winding -Low voltage winding -Neutral winding	kV kV kV	170 - 95
Short-circuit impedance Voltage Ucc	%	4% (±10%)
Non load losses P0	W	≤145
Load Losses Pcc	W	≤1750
Noise level Lwa	dB	<50
Maximum ambient temperature	°C	40
Tank type	-	Sealed tank with bolted cover
Maximum temperature rise oil/windings	°C	≤50°C/55°C
Tests	-	Winding resistance, voltage ratio and phase displacement, no-load loss & current, load-loss and short circuit impedance, induced and separate source voltage withstand test.
Color	-	RAL7033
Spare parts	-	Oil gauge with thermometer, repair paint, and silica gel for breather
Guarantee	-	1 year from the date of taking over certificate of the project.

Detailed Photos

Reference

Our Performance

No.	Service Stage & Details
1	Pre sale service
a.	Make technical solution
b.	Send quotation, technical data sheet and drawing
c.	Prepare power transmission plan, testing plan, and shipment plan
2	In sale service
a.	Supervise the manufacturing schedule totally in accordance with the plan
b.	Send photos to customer during every manufacturing process (hold point)
c.	Inform the customer one week before testing
3	After sale service
a.	Installation and commissioning, training the workers
b.	Quick response within 12 hours any time
c.	Provide 12 months guarantee period normally

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Frequently Asked Questions

1. What is the primary purpose of a grounding transformer?

A grounding (or earthing) transformer provides a ground path to an ungrounded wye or delta-connected three-phase power system, allowing phase-to-neutral loads to be accommodated by providing a return path for neutral currents.

2. What are the typical winding configurations for grounding transformers?

They most commonly feature a single winding transformer with a zigzag configuration, but they can also be created utilizing a wye-delta winding configuration.

3. Where are neutral grounding transformers most commonly applied?

Neutral grounding transformers are commonly applied to generators in power plants, wind farms, and on high-voltage (sub-transmission) systems such as 33 kV networks where a ground connection is otherwise absent.

4. What features of this earthing transformer prevent wear and noise?

The transformer utilizes a phase-shaped core with three joints, and curing paint is brushed on the surface to significantly reduce physical wear, tear, and operational noise.

5. What kind of after-sales support and guarantee is provided?

After-sales support includes installation, commissioning, worker training, and a quick response within 12 hours. A standard guarantee of 1 year is provided from the date of the project's taking over certificate.