C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL 2-1C70 Capacitor Bank Protection and Control SystemChapter 2: Product descriptionProduct descriptionThis chapter outlines the product, order codes, and specifications.2.1 Product descriptionThe C70 Capacitor Bank Protection and Control System is part of the Universal Relay (UR) series of products. It is amicroprocessor-based relay for protection and control of small, medium, and large three-phase capacitor banks. The relaycan be ordered with up to three current transformer/voltage transformer (CT/VT) modules, allowing for flexible applicationin variety of bank configurations.The key protection functions cover grounded and ungrounded, single and parallel banks. Sensitive protection functionssupport compensation for both external (system) unbalance and inherent unbalance of the capacitor bank itself. Bothvoltage and current-based balance protection functions are available. Algorithms are developed to automatically selectcompensation settings after repairs or other alternations of the bank.The relay supports a variety of bank configurations through flexible configurations of its AC inputs, installed voltage andcurrent transformers, and resulting protection techniques.The relay incorporates an automatic voltage regulator (AVR) responding to voltage, reactive power, or power factor. Aseparate timer function initiates controls on a pre-defined time/date basis. These on-off type controls are meant toautomatically close or open the associated breaker. A supervisory function is provided to program the local/remote, auto/manual functionality, temporary inhibit closing after tripping, and other auxiliary functions, such as operation counters.A capacitor control element provides remote/local and auto/manual control regulation, trip/close interlocking, and seal-in.A user-programmable time delay inhibits closing until after the bank discharges itself to a safe level.The relay can also equipped with a serial 64/128 kbps direct input/output module for fast and reliable peer-to-peercommunication with other UR-series devices.The C70 metering functions include true root mean square (RMS) and phasors for currents and voltages, current andvoltage harmonics and total harmonic distortion (THD), symmetrical components, frequency, power, power factor.Diagnostic features include an event recorder capable of storing 1024 time-tagged events, oscillography capable ofstoring up to 64 records with programmable trigger, content and sampling rate, and data logger acquisition of up to 16channels, with programmable content and sampling rate. The internal clock used for time-tagging can be synchronizedwith an IRIG-B signal, using the Simple Network Time Protocol (SNTP) over the Ethernet port, or using the Precision TimeProtocol (PTP). This precise time stamping allows the sequence of events to be determined throughout the system. Eventscan also be programmed (via FlexLogic™ equations) to trigger oscillography data capture that can be set to record themeasured parameters before and after the event for viewing on a computer. These tools significantly reducetroubleshooting time and simplify report generation in the event of a system fault.
