Neutral Grounding Transformer Panel Box

Neutral Grounding Transformer Panel Box Ambient Temperature: -40 - 40celsius Max Elevation: 3000m Max Humidity:90%

Brife Introduction of Neutral Grounding Transformer Panel Box

1.1   Selection of Generator Neutral Grounding Mode 

Generator is the driving force in power system, which must have the right ability to respond to sudden failure in operation, to which the mode of generator neutral grounding is closely related.

*solid grounding

*Neutral-point grounding via low-resistance

*Neutral-point ungrounded

*Neutral-point grounding via arc-suppression coil

*Neutral-point grounding via high resistance

1.2   Model of Generator Grounding via High Resistance 

The generator neutral point grounding via high resistance is able to effectively restrain fault current, thereby effectively preventing the stator wound from breaking down, and lowering transient over-voltage due to arc flash ground.

There are a number of solutions for neutral point grounding via high resistance, among which, the combination of single-phase grounding transformer with resistor is the best. The MRD-FD grounding type of resistor cabinets produced by our company is of small size and light weight. Grounding transformer is shock-resistant, fire-retardant, and with small PD. The resistor is made from special materials, possessing stable performance and strong through-flow capability.

2.1  Scope of Application

MRD-FD type generator neutral-point resistor cabinet is complete equipment specially used by generators in power plant which adopts high-resistance grounding for neutral-point. The voltage grade for generator mainly ranges 6kv to 20kv. When the stator adopts one-point grounding, it is able to limit the grounding current to very small value, and effectively restraint electric-arc grounding transient over-voltage.

3 Recommended Technical Parameters of MRD-FD Type Generator Neutral Resistor

Generator capacity(MW)	100/125		200	300		600		900/1000
Generator nominal voltage(kV)	10.5	13.8	15.75	18	20	20	24	24	27
Expected loop single-phase grounding max.capacitance current(A)	4		5	6		8		10
Grounding transformer primary side voltage(kV)	10.5/	13.8/	15.75/	18/	20/	20/	24/	24/	27/
Grounding transformer secondary side voltage (kV)	0.22		0.22	0.22		0.22		0.22
Grounding transformer nominal capacity(kVA)	30		30	50		50		63
Secondary side resistance value (Ω)	1.0		0.8	0.5		0.4		0.3
Grounding protection tap voltage(kV)	0.1		0.1	0.1		0.1		0.1

Neutral Grounding Transformer Panel Box