Substation & Switching Basic Training

[Audio] Welcome to the Origis Services, Substation and Switching Basic Training Module..

[Audio] A substation is typically separated into four major components. The high side or H V side, The G S U or transformer, the M V side or low side, and the control building..

[Audio] Lethal voltages are present within the substation. Be mindful of objects, tools, or appendages that could come close to or in contact with energized conductors..

[Audio] First, let's look at Generator Step Up Transformers.

[Audio] A transformer is a device that is used to step AC voltage up and down. These devices use a magnetic field created in one winding, the primary winding, to create a proportional voltage in a secondary winding. As voltages go up, the current required for the same load goes down. This makes transformers useful for stepping up the relatively low voltage high-current power created by inverters, into high-voltage low current for transporting electricity across transmission lines..

[Audio] The oil inside a transformer serves two primary purposes. First, it insulates the wires inside the winding and the transformer tank from each other. Secondly, it provides a medium for the heat generated within the core of the transformer to be removed via the cooling fins. As with most matter, oil expands when it heats up. The conservator tank provides somewhere for the expanding oil to go where it won't cause leaks or other damage to the transformer. Typically, a bladder is used to protect the oil from coming in contact with the outside air..

[Audio] The dehydrating breather allows the air inside the conservator bladder to expand and contract. The conservator bladder is not pressurized but is allowed to flow freely in and out of the bladder. The dehydrating breather contains silica desiccant beads that absorb the moisture present in the air, to extend the life of the conservator bladder. Typically, the beads start out a bright color like pink or blue. As the beads absorb moisture, they turn to a white color, indicating the need for replacement..

[Audio] Transformer bushing are devices that allow the high voltage conductors to penetrate the transformer tank without touching the sides, or anything else which would cause a fault. These bushings are typically filled with oil to insulate the conductors. It is important to monitor the level of oil within these bushing to prevent failure..

[Audio] There are several different types of gauges that can be present on a transformer. Most often you will see temperature and pressure gauges. These should be monitored, and their values recorded during the substation inspection..

[Audio] Radiators allow the ambient air to cool the oil inside the transformer. The large surface area of the fins creates a convective cooling effect that is compounded by the airflow created by the fans..

[Audio] The Buchholz relay is designed to protect the transformer from failing catastrophically during an arcing event inside the transformer. An insulation failure inside transformer causes arcing which generates flammable gasses such as hydrogen & acetylene. These gasses float to the top of the transformer and into Buchholz relay, causing the relay to trip. This relay can also be activated by sudden flow of oil, or by accumulation of gasses in top of transformer..

[Audio] Let's look at Medium-Voltage Equipment next..

[Audio] Feeders from the collection system terminate here. Feeders typically connect to the substation bussing through manually operated knife switches that are used to isolate individual feeders from the rest of the plant. These switches are designed to be opened and closed under no-load conditions. They should only ever be operated after it has been verified that the switch is not carrying any current. Opening the switch under load will cause a failure of the switch..

[Audio] Current transformers operate on the same principle as any other transformer. These devices use a secondary winding around the primary conductor to create a proportionally lower current that the substation's instrumentation can measure safely. The measurement devices use an equation or ratio to determine the actual current present on the conductor. For example, in a 100:1 winding, measuring 10 amps on the secondary winding would mean that 1000 amps are present on the primary..

[Audio] Potential transformers also operate on the same principle as current transformers, except they are used to step down the VOLTAGE to a level that the substations instrumentation can measure safely. These devices also use the stepped-down measurement to calculate the actual voltage present on the primary conductor..

[Audio] Breakers are the primary switching devices inside a substation. They are designed to operate quickly in case of a fault within the system. The substation monitors the current flowing through each breaker and if an over-current condition is detected, the breaker opens, isolating the fault..

[Audio] The station service transformer is practically identical to the transformer that sits out on the pole outside your house. It provides 120 and 208 volts to the substation control house and ancillary equipment such as lighting..

[Audio] Gang operated disconnects are functionally similar to the manually operated disconnects we discussed earlier, but all 3 phases move in unison when operated. These switches can be operated manually, or motor-driven..

[Audio] High-Voltage Equipment. High-Voltage Equipment.

[Audio] Current transformers on the high side of the substation work exactly the same way as the current transformers on the low side..

[Audio] Capacitively coupled voltage transformers or CCVT's allow the substation meters to measure the extremely high voltage present on the high side by creating a voltage divider using capacitors. These devices also step down the voltage to a level safe to measure..

[Audio] A breaker provides over-current protection for GSU/Substation Contains Sulfur Hexa-fluoride (SF6) insulating gas SF6 is a highly-regulated greenhouse gas, but is not toxic Each phase has a gauge to monitor pressure, any pressure loss should be reported immediately.

[Audio] Air disconnect switches on the high side of the substation operate in the same fashion as those on the low side. These switches may also be manually driven, or coupled with a motor operator..

[Audio] The tie-in structure supports the load of the jumpers connecting the transmission line to the substation..

[Audio] The optical grounding wire or O P G W serves two purposes. The first is to operate as the grounding wire that bonds all of the transmission line towers together. The second purpose is to carry the fiber optic cable that connects the substation to the next substation at the other end of the transmission line and may also provide internet access to the site..

[Audio] Have you ever been inside a substation Control Building ?.

[Audio] The primary devices located within a substation control house are the protective relays. These devices monitor all of the equipment within and connected to the substation thousand of times per second. If an anomaly is detected, such as an underground fault, the relay will signal the breaker to open. The data that these relays are monitoring are stored on the device when an issue is detected. This data can be retrieved for analysis to aid in locating a fault or making repairs..

[Audio] Control switches are used to manually control breakers and switches in the substation yard. In general, a green light means a breaker is opened, and red means it is closed. Turning the handle one way or the other will trip or close the breaker. Exercise caution when standing or walking in the control house. Keep a safe distance from these switches to avoid accidentally operating a switch..

[Audio] Marshalling or termination cabinets are a place for the wires connecting all of the equipment in the yard to be terminated and connected to the equipment inside the control house. Care must be taken when opening these cabinets. Disturbing a loose connection may cause an unintended trip..

[Audio] Revenue meters are devices used to record the energy produced by the plant and sold to the "off-taker". These meters use the current and potential transformers on the high side of the substation to record the total energy produced in kilowatt-hours..

[Audio] Substation backup batteries provide a steady 120 volts D C to the substation equipment. Typically, all breakers and relays, and some switches are operated on the 120 volts D C system. These batteries are essential to the operation of the substation equipment. NERC requires that these batteries are maintained regular, and that maintenance documented for future reference..

[Audio] This table shows an example of the maintenance required for a valve-regulated battery system..

[Audio] The battery charger maintains and monitors the battery system. Many charges will trigger an alarm if an issues is detected within the battery system..

[Audio] Both A C and D C breaker panels are present within the control house. AC breaker panels are fed by station service 120 V A C and Supply power to ancillary devices like yard lights, A/C units, non-essential network equipment. DC Breakers are fed from battery bank 120 V D C and supply power to essential devices like substation breakers, relays, and Power Plant Controller..

[Audio] If a substation has backup power from another source such as a generator, a transfer switch will control which source powers the substation controls. Typically, the power will be provided by the station service transformer, but in the event of an outage a generator may supply power..

[Audio] The Power Plant Controller primarily monitors and controls the inverter and their output. The PPC receives setpoints from the grid and the Remote Operations Center and sets the power output from each inverter in response to those set points..

[Audio] Switching is any planned or unplanned operation that changes the state of a switch, breaker, fuse, disconnect or other component within the primary electrical system of a substation, switchyard, or collection system. Emergency Switching is switching that is performed to mitigate an IMMEDIATE danger to people or equipment. Loss of energy production or revenue DOES NOT constitute an emergency. Origis Services policy must be followed for ALL switching activities. For any switching activity, a Qualified Switchman, or Switchman-In-Training must be present on site during the activity..

[Audio] A Requestor is an Individual that identifies a need for switching to perform work safely. A Dispatcher is an Individual within the AROC that reads switching procedure and instructs Switchman on each step of the switching activity. A Field Dispatcher someone who is reading the switching procedure and instructing the Switchman on each step of the switching activity in the case it is not feasible to use the AROC as the dispatcher..

[Audio] A Qualified Switchman is and Individual that Origis Services has determined qualified to supervise/perform switching activities, approve switching procedures, and can dispatch other Qualified Switchmen or Switchmen-in-training. A Switchman-In-Training is someone who is undergoing training and evaluation for substation switching by a qualified Switchman. This person is qualified to perform switching under the supervision and approval of a qualified Switchman..

[Audio] Origis Services has a written form that must be used to request and perform a switching operation. An example is shown here..

[Audio] When a need for switching is identified, the requestor will contact the site lead. The site lead will review the scope of work and fill out the switching order form. The site lead will review the form and discuss any changes that need to be made to safely isolate the equipment to be worked on. Once the procedure is approved by the qualified switchman, the switchman will send the form to the AROC for review. The AROC will make any notifications necessary for compliance. The Transmission operator and off-taker, for example. Once all notifications have been made, the AROC will notify the site lead and switchman..

[Audio] In accordance with NERC requirements, all switching activities MUST utilize 3-part communication and the NATO phonetic alphabet between dispatcher and switchman. These requirements apply to all Origis Services sites, not just NERC registered facilities. All other personnel should leave the area where the switching is taking place to avoid distractions and maintain safety (a "safety second" person may remain in the area). No switching activities may take place in the substation without a Qualified Switchman or Switchman-in-training on site during the activity. If a Switchman-in-training is used, the procedure must be reviewed together with a Qualified Switchman prior to beginning. If at any time equipment is found to be in a state different than expected, STOP, and contact the Qualified Switchman before proceeding..

[Audio] Here is an example for communication between the dispatcher and switchman. Note the use of the NATO phonetic alphabet and 24 hour time format..

[Audio] The use of the NATO phonetic alphabet helps avoid errors and misunderstandings when communicating during a highly important activity such as substation switching..

[Audio] If at any time, you have questions or concerns regarding switching, immediately reach out to your supervisor.