Auxiliary power supply requirements for a circuit breaker. AC supply is provided for heating, cubicle lighting, etc. DC supply is provided for tripping coil, closing coil, and in-built protection system. Both AC and DC supply can be provided for spring-charged motor since several manufacturers of a universal motor. Auxiliary power supply requirements for power transformer. AC supply is provided for transformer cooling fan, heating, cubicle lighting, transformer monitoring system, and oil DC motors. Auxiliary power supply requirements for this connector and earth switch. The AC supply is provided for heating, cubicle lighting, and motor operating mechanism for closing and opening. Auxiliary power supply requirements for skater. AC supply is provided for computers, GPS, gateway supply, and timer. Auxiliary power supply requirements for control, protection, and monitoring system. DC supply is provided for Antitheater panel, control, and protection panels, telecommunication system, fire detection system, firefighting system, and public address system. It does not apply reductions of status monitoring equipment and the regional circuits fall under the category of vital loads. They will be supplied from DCUPS as changeovers from one source to another are seamless. All motors used for isolator operating mechanism, transformer cooler fans, or ELT mechanism are usually of a three-phase induction motor type. As these loads fall under the category of essential loads, they have to be fed from switch gear, or DB having two sources. Slight delay in planned operation that may be due to delay in changeover may not result in any damages. Spring charging motor of CB is usually operated at AC or DC. Universal motor, depending on manufacturer's design. Where it is AC operated, it will be fed from essential switchboard. If it is DC operated, power supply shall be from DCUPS. HVAC loads are operated on AC power. They may be classified as non-essential in India. In such cases, we switch gear with a single income will be sufficient. HVAC loads are classified as essential in other geographical areas like Middle East, where air conditioning after substitution is essential to keep the temperature rise of equipment within permissible limits. In the absence of air conditioning, ambient temperature to be considered for design of indoor equipment will be high, and the IEC rated equipment requires rating heavily to ensure safe operation at such high ambient temperature. In such cases, they shall be connected to an LED switch gear having two sources. Lighting loads are by enlarge, are classified as non-essential. However, a portion of lighting is required to carry out emergency works are considered as essential. Some lighting, which is meant for lighting up of escape path to ensure safe evacuation of personnel is classified as vital. In highly secured installations, are in installations having strategic importance, thin sliding will be regarded as essential load. Lighting loads are connected to AC power. Emergency lighting is normally connected to standby DG if available. Escape lighting is connected to UPS. Emergency or escape lighting may also have self-contained battery backup within each fixture. Small power loads, water pumps are easily operated. They are classified as a non-essential load, as they can resume their functions a few hours later also, without adversely affecting the functionality in a major way. As they are classified as a non-essential loads, they can be connected to DB with single power source. Anti-condensation heaters are generally non-essential loads fed from AC power. However, some applications require heaters to be on all ways for proper functioning of certain equipment. In such cases, they will have to be fed from essential switchboard. DCS or SCADA or RVU and related service or land equipment, or HMI, are operated on AC power, loss of power supply, to DCS or SCADA, RVU will result in overall chaos in the remote control room. And all processes are operating interlocks would become dysfunctional. As they are regarded as vital loads, they shall be fed from ACUPS. CCTV or BAG systems are generally regarded as vital systems. Otherwise, security surveillance would be compromised and emergency public addressing would become dysfunctional at crucial time. They are fed from ACUPS. Telecom systems are classified as vital loads as communication of voice and data are crucial for proper functioning of equipment. They are usually fed from 48 volts of DCUPS. Here is a quick recap of what you've learned thus far. The electrical power, which is required for the satisfactory control, monitoring, operation, and maintenance of the substation equipment and allied services is termed as auxiliary power. Auxiliary power is usually at low voltage and can be both AC and DC. If a substation loses its auxiliary power, it could result in loss of control, protection or trip circuits, status monitoring, interlock circuits, non-operation of motor loads, and associated functions. Non-functioning of HVAC, firefighting, lighting, and small power loads. Failure of skater, CCTV, and telecom systems. On loads are classified as vital, essential, and non-essential. Vital loads are those loads in the absence of power supply could result in injury or loss of life or assets. Essential loads are those loads in the absence of power supply could result in loss of revenue or production or impact quality of the product. Non-essential loads are such loads which do not fall under the category of both vital and essential loads. The auxiliary power supplied requirements of substitution equipment can be either AC or DC. Vital loads shall receive power from the AC or DCUPS as applicable. Essential loads shall be fed from switchboard connected to redundant sources. Non-essential loads may be fed usually from only one source.
