IS 1180 (Part I) specifies the requirements for three-phase oil-immersed transformers, which are used in various power systems. Here are the key specifications and requirements for three-phase transformers according to this standard:
### 1. **General Requirements:**
- **Purpose:** IS 1180 (Part I) covers the design, construction, and performance requirements for three-phase, oil-immersed transformers intended for use in electrical power systems.
- **Rating:** The standard applies to transformers with ratings up to and including 100 MVA and voltages up to 33 kV.
### 2. **Constructional Features:**
- **Core:** The core should be constructed of high-grade silicon steel to minimize losses. It should be designed to minimize eddy current losses and magnetic flux leakage.
- **Windings:** Windings can be made of copper or aluminum. They should be properly insulated and designed to handle the rated voltage and current.
- **Insulation:** The insulation system should be capable of withstanding the rated voltage and temperature conditions. Typically, it includes paper-insulated oil or synthetic insulation.
- **Tank:** The transformer tank should be robust, leak-proof, and capable of withstanding mechanical stresses during operation.
### 3. **Electrical Characteristics:**
- **Voltage Ratings:** The transformers are designed for standard voltage ratings, usually up to 33 kV.
- **Frequency:** They are typically designed for a nominal frequency of 50 Hz (or 60 Hz in some cases).
- **Temperature Rise:** The standard specifies the allowable temperature rise for various parts of the transformer to ensure safe operation and longevity.
### 4. **Testing:**
- **Routine Tests:** Routine tests must be conducted on all transformers and include tests like insulation resistance, transformer ratio, and winding resistance.
- **Type Tests:** These are more comprehensive and include tests such as temperature rise, insulation strength, and short-circuit withstand capability.
- **Special Tests:** Depending on the specific requirements, additional tests such as partial discharge tests or noise level tests may be required.
### 5. **Performance Requirements:**
- **Efficiency:** The transformer should meet specified efficiency standards under full load and part load conditions.
- **Regulation:** The voltage regulation should be within the limits specified by the standard to ensure stable voltage output.
- **Short-Circuit Withstand:** The transformer should be designed to withstand short-circuit conditions without catastrophic failure.
### 6. **Safety and Environmental Considerations:**
- **Protection:** The transformer should have appropriate protection features such as pressure relief devices, temperature sensors, and overcurrent protection.
- **Oil Handling:** The insulating oil used should meet the specified quality and handling requirements to avoid environmental contamination.
### 7. **Marking and Documentation:**
- **Nameplate:** The transformer should have a nameplate with essential information including voltage ratings, power rating, and manufacturer details.
- **Documentation:** Comprehensive documentation should be provided, including operation manuals, maintenance guidelines, and test certificates.
These specifications ensure that three-phase transformers meet the necessary performance, safety, and reliability standards required for their application in power systems. For the most detailed and specific requirements, referring to the full IS 1180 (Part I) document is recommended.