Integrity or continuity of the stabilising resistor for high impedance busbar protection scheme is of paramount importance.I have seen two cases where the slider ring of the variable stabilising resistor was broken probably due to excessive tightening of the slider screw. Has any one else...
In our system few old Substations run with 32 V DC power supply. We would like to standardise on 125 V DC rated relays which are used in majority of the substations. In that context do you see any issue if we power 125 V rated relay by an external 32/125 volt step up convertor?
Regards,
What is the general practice of grounding the sheath of control cables especially in HV substation/ switch yard. Do you ground the sheath or screen of the cable only at one end or at both the sends of the control cable?
Most of us know that during planned outage of primary plant/equipment its customary to isolate all possible points/sources of energisation and secondary of voltage transformer being one of them. Our issue is that we also check for the status of PT/VT mcb as one of the condition required to close...
Does any member has experience or know of the possibility of distance relay's inability to perform as designed due to suppression of negative sequence current or limited positive sequence current contribution from voltage source converters commonly applied at HVDC stations? I have heard that...
We all know that protection relays at time may not work satisfactorily under very low fault level on the network. What is your opinion or practise in dealing with this issue?
Is there any use of enabling Power swing blocking in a distance relay on radial connected line (of 30 km long) to Hydro generator of 50 to 80 MW capacity?
Hi- We all know that in order to generate zero seq voltage from a VT/PT there need to be a path for zero sequence flux to flow i.e. in other words the VT needs to be either 3 x Single phase VTs or a five limb and star point of the primary winding needs to be grounded.
My question is can...
Sometime CT secondaries are connected in series to increase knee point voltage as each CT need to supply only half the burden voltage.
The question is what happens when there is a primary fault in between the two CTs as shown in attached...
SEF protection on 11 or 22kV distribution feeder is set very sensitive to detect high resistance fault yielding mere 10 amp primary current.Such scheme is checked by relay fed from the CT on neutral of transformer.This is done to improve security of the scheme as SEF needs real current to be...
Could any please confirm or contradict my understanding regarding distribution of fault current between hv and lv winding of a YN (ungrounded)/YN(grounded) transformer for phase to ground fault on lv side.As permy understanding the fault current distribution on hv side will be 1:1:2 ratio for...
We have a legacy practice of not allowing peeople to enter live switch yard if busbar protection is out of service and wonder what is your experience or practice in this regards?
thanks for your input in advance
Does it matter if the primary conductor carrying the current is not positioned at centre of the toroidal CT? will it introduce any errors due to asymmetrical flux linkage?
Does someone know of a df/dt relay whose setting can be changed via DNP 3 or Modbus command? We are designing a special protection scheme wherein df/dt set point of the relay will be altered via DNP or Modbus command from EMS(energy management system)depending upon system inertia i.e. depending...
Just wondering what will happen if one inadverently comes in contact with one phase of 22kV feeder conductor fed via ungrounded source? I have read that such a system will sustain fault current due to phase to ground capacitances[highlight ][/highlight] of healthy phases.Could this capacitive...
