Hello everyone,
For a small 15 MW GT Plant, we have a turbogenerator rated at 11 kV with high impedance grounding (through T/F resistance).
The output of the generator is connected to a MV switchgear through medium voltage cables before leaving the MV swg to the Step Up T/F primary.
Due to the high impedance grounding scheme of the generator, the a.m. electrical equipment were specified for a rated voltage of 15 kV (17.5 kV).
Acc. to my knowledge, for a higher output GT generator, the Generator CB has surge capacitors and surge arresters,
both before and after the switching element to compensate for overvoltage surges.
These were also specified for the current, lower output project, creating difficulties to the MV switchgear vendor.
Namely, he expressed difficulty in proccuring a 17.5 kV MV switchgear with short delivery time and questioned if the surge capacitors & surge arresters
can be incorporated in the cable compartments of the GCB & outgoing cubicles.
1) Do you have any experience of a MV switchgear assembly rated at 20 kV (24 kV) using a 17.5 kV rated GCB? Is this possible?
Fyi the MV switchgear manufacturer produces and type tests the assembly while using well known manufacturers for the circuit breakers.
2) I have an example of a MV switchgear GCB cubicle of an older project that had surge arrestors & surge capacitors in the cable compartment,
but when I searched for this option at the manufacturers catalogues he does not mention them.
Is this option something standard or is it custom made for specific projects?
For a small 15 MW GT Plant, we have a turbogenerator rated at 11 kV with high impedance grounding (through T/F resistance).
The output of the generator is connected to a MV switchgear through medium voltage cables before leaving the MV swg to the Step Up T/F primary.
Due to the high impedance grounding scheme of the generator, the a.m. electrical equipment were specified for a rated voltage of 15 kV (17.5 kV).
Acc. to my knowledge, for a higher output GT generator, the Generator CB has surge capacitors and surge arresters,
both before and after the switching element to compensate for overvoltage surges.
These were also specified for the current, lower output project, creating difficulties to the MV switchgear vendor.
Namely, he expressed difficulty in proccuring a 17.5 kV MV switchgear with short delivery time and questioned if the surge capacitors & surge arresters
can be incorporated in the cable compartments of the GCB & outgoing cubicles.
1) Do you have any experience of a MV switchgear assembly rated at 20 kV (24 kV) using a 17.5 kV rated GCB? Is this possible?
Fyi the MV switchgear manufacturer produces and type tests the assembly while using well known manufacturers for the circuit breakers.
2) I have an example of a MV switchgear GCB cubicle of an older project that had surge arrestors & surge capacitors in the cable compartment,
but when I searched for this option at the manufacturers catalogues he does not mention them.
Is this option something standard or is it custom made for specific projects?
