NABCEP ESIP flashcards
NABCEP ESIP · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Usable energy
- Nameplate energy multiplied by allowable depth of discharge and by the end-of-life capacity retention factor; this is the energy the system can actually deliver at the end of its warranty period.
- Round-trip efficiency
- Ratio of AC energy discharged to AC energy required to recharge over a full cycle, including inverter, transformer, and auxiliary losses. Design loads must be grossed up by its inverse.
- C-rate
- Charge or discharge power in kW divided by energy capacity in kWh. A 100 kWh pack discharged at 50 kW operates at C/2, a two-hour rate.
- Depth of discharge
- Fraction of rated capacity removed during a discharge cycle. Deeper cycles yield more usable energy per cycle but generally reduce cycle life.
- State of charge
- Remaining energy in the battery expressed as a percentage of current usable capacity. It is an estimate derived from voltage, current integration, and BMS algorithms.
- Continuous load factor
- Code rule requiring conductors and overcurrent devices serving continuous loads to be sized at 125% of the continuous current, applied to inverter AC output and battery DC circuits.
- Voltage window check
- Verification that series string voltage stays within inverter battery input limits from full charge to low-voltage cutoff, accounting for cold-temperature voltage rise and line drop.
- DC short-circuit current rating
- Maximum fault current the battery and its protection can safely interrupt at system voltage. Disconnects and fuses must have an interrupting rating at least equal to it.
- Autonomy days
- Number of days a standalone storage system must serve the load without recharge. Nameplate energy equals daily load times autonomy days divided by usable-energy factor.
- Torque verification
- Tightening DC lugs and busbar hardware to the manufacturer's published value with a calibrated wrench, then recording values. Loose terminations cause heating and fire risk.
- Polarity check
- Confirming positive and negative conductors are correct at each string and at the inverter before energizing, preventing reverse-current damage on shared DC buses.
- Shielded communication cable
- Twisted-pair cable with a shield used for CAN or RS-485 links between BMS, inverter, and gateway. Shield is terminated at one end to prevent ground loops.
- Working space clearance
- Code-required depth of accessible and illuminated space in front of electrical equipment, kept clear of battery cabinets and other obstructions for safe servicing.
- Equipment grounding conductor
- Conductor bonding non-current-carrying metal parts of racks, enclosures, and cabinets to the grounding system, establishing a low-impedance fault return path.
- Insulation resistance test
- Measurement of DC circuit insulation to ground before energizing, typically required to exceed one megohm at the manufacturer's specified test voltage.
- Low-temperature charging limit
- Minimum cell temperature at which charging is permitted. Charging below it causes lithium plating, permanent capacity loss, and possible internal short circuits.
- Rapid shutdown
- Function that reduces DC conductor voltage at the array or battery to a safe level for responders. Required locations and labeling depend on code edition and jurisdiction.
- Commissioning sequence
- Ordered process: inspection, torque and insulation checks, firmware verification, then functional and performance testing, with every result recorded as the baseline.
- Closed-transition transfer
- Brief paralleling of inverter output with the grid during transfer so the load sees no interruption. Testing confirms no unintended export and correct anti-islanding behavior.
- Capacity performance test
- Controlled discharge at a defined C-rate to cutoff, measuring delivered AC energy and round-trip efficiency, then comparing results with expected usable energy.
- Voltage and frequency trip settings
- Protection thresholds and clearing times programmed per the applicable interconnection standard, verified during commissioning along with ride-through and reconnect delays.
- Communications chain test
- End-to-end verification that BMS, inverter, gateway, and monitoring portal exchange data, with telemetry, alarms, and state-of-charge readings matching local values.
- Commissioning baseline record
- Documented torque logs, insulation values, firmware versions, setpoints, and test results captured at startup, used later to detect degradation or unauthorized changes.
- Emergency shutdown test
- Verification that actuating the emergency stop opens battery contactors, disables the inverter, and places the system in a safe state without relying on software alone.
- Top-of-charge balancing
- Holding cells at full charge so the BMS can equalize series cell voltages. Persistent imbalance at commissioning predicts reduced capacity and warranty claims.
- State of health
- Current capacity divided by initial capacity, expressed as a percentage. Warranties commonly guarantee 70 to 80 percent retained energy at a stated cycle count.
- Calendar aging
- Capacity and resistance degradation that occurs over time regardless of cycling, accelerated by elevated average cell temperature and high state of charge.
- Cell voltage spread
- Difference between highest and lowest series cell voltages under the same conditions. A widening spread indicates imbalance or an incipient cell failure.
- Thermal management inspection
- Scheduled check that fans, coolant loops, filters, and temperature sensors operate within specification, keeping cells in the range that preserves design life.
- Alarm log trending
- Reviewing historical fault and warning records for patterns such as repeated over-temperature or over-voltage trips, which point to airflow, setpoint, or degradation problems.
- DC arc flash hazard
- Danger of sustained DC arcing from energized battery circuits even when the AC side is off. Lockout/tagout and DC-rated PPE are required for maintenance work.
- Firmware change log
- Record of version, date, and reason for each software or setpoint update. Undocumented changes invalidate performance baselines and may void manufacturer warranties.