Table of Contents
- 1 What is protection relay setting?
- 2 What type of relay protection can be given for the all types of internal faults in transformer?
- 3 How do you calculate protection relay?
- 4 Which relay is used for protection of feeder?
- 5 Which relay is used for generator protection?
- 6 Which relay is used for feeder?
- 7 What type of relay is used for transformer protection?
- 8 Why are delta-wye transformers bad for ground fault protection?
What is protection relay setting?
In this method, an appropriate time setting is given to each of the relays controlling the circuit breakers in a power system to ensure that the breaker nearest to the fault opens first.
Which relay is used for providing protection to 11kv feeder?
Relays for Transmission & Distribution Lines Protection
| SL | Lines to be protected | Relays to be used |
|---|---|---|
| 4 | 33 KV lines | Non-directional IDMT 3 O/L and 1 E/L relays. |
| 5 | 11 KV lines | Non-directional IDMT 2 O/L and 1 E/L relays. |
What type of relay protection can be given for the all types of internal faults in transformer?
Transformer protection methods
| No. | Fault Type | Protection used |
|---|---|---|
| 1. | Primary winding Phase-Phase fault | Differential; Overcurrent |
| 2. | Primary winding Phase-Earth fault | Differential; Overcurrent |
| 3. | Secondary winding Phase-Phase fault | Differential |
| 4. | Secondary winding Phase-Earth fault | Differential; Restricted Earth Fault (REF) |
Which protection would you recommend as a primary protection for 250 MVA power transformer?
While for all small size distribution transformers, only high voltage fuses are used as main protective device. For all larger rated and important distribution transformers, over current protection along with restricted earth fault protection is applied.
How do you calculate protection relay?
Calculation of Over Current Relay Setting:
- Over Load Current (In) = Feeder Load Current X Relay setting = 384 X 125\% =480 Amp.
- Required Over Load Relay Plug Setting= Over Load Current (In) / CT Primary Current.
- Required Over Load Relay Plug Setting = 480 / 600 = 0.8.
What are the types of protection relays?
Basic classification of protective relays includes:
- Electromagnetic Relays: Armature. Induction cup / induction disc.
- Static Relays: Analog input signals are processed by solid state devices.
- Digital / Numerical Relays: Uses programmable solid state devices based on digital signal processing.
Which relay is used for protection of feeder?
differential relay
The differential relay is used for the protection of the feeder, large busbars, etc.
What is a feeder protection relay?
Feeder protection, or more exactly protection for overhead lines and cables, is the most commonly used type of protection. The protection has to ensure that the power grid continues to supply energy. The relays also have to minimize damage to the cables and other connected equipment and to ensure safety for everyone.
Which relay is used for generator protection?
Reverse power relay is used for this purpose. As soon as the generator starts rotating in motoring mode, the reverse power relay will trip the generator set.
Which relay is used for motor protection?
To protect against motor damage, we mustensure that this condition is not reached, hence we must trip the motor before the overload limit (service factor) is reached. The relay most commonly used for this purpose is the induction disc relay.
Which relay is used for feeder?
Translay relay: The translay relay is a differential relay. The arrangement is similar to overcurrent relay, but the secondary winding is not closed on itself. These types of relays are used in the feeder protection and the scheme is called the Translay scheme.
What is time multiplier setting?
Time Setting Multiplier (TSM): The time setting multiplier is nothing but an adjusting or speeds up the tripping mechanism of the relay (it is called as the dial). The dial is nothing but a rotating disc, which rotates when the fault current in the relay coil reaches the pickup current.
What type of relay is used for transformer protection?
For transformers 10 MVA and above, which falls under (Category III & IV), differential relays had to be used to protect them. Additionally, mechanical relays such as Buchholtz relays, and sudden pressure relays are widely applied for transformer protection.
What is the technical specification of 33/11kv sub-station (10 &16 MVA)?
Technical specification of 33/11kV Sub-Station (10 &16 MVA) 1-35 1. SCOPE OF THE TENDER The tender includes for the supply , manufacture testing , backing , erection design , shipping , delivery C&F Baghdad of sub-Stations each comprising the following : 1-1 The 33 KV indoor switchgear
Why are delta-wye transformers bad for ground fault protection?
If there is upstream relaying on a delta-wye transformer, any zero-sequence current can be assumed to be from a primary ground fault, allowing very sensitive ground fault protection. On a wye-wye, a low-side ground fault causes primary ground fault current, making coordination more difficult.
Should protection schemes be tied to the MVA or primary kV?
There is some tendency to tie protection schemes to the MVA and primary kV of a transformer. While there is some validity to this approach, there are many other issues to be considered. Issues to be considered include: •The severity of personnel safety concerns and the possibility that a given protection scheme can reduce these risks.