• Emco Electronics

Automatic voltage regulating relay, type EE-302

Emco Electronics offers microcontroller-based automatic voltage regulating relay type EE-302. This is a new generation relay used for regulating the secondary voltage of power transformers with a motor driven on load tap changer (OLTC). A single control pulse to the motor causes a change in voltage by one step. When step by step function is inactive, the motor drive is controlled by a continuous control pulse. A "Raise" or "Lower" control signal is generated by the voltage regulator when the measured voltage deviates from preset conditions. The regulated voltage can be displayed in volts, kilovolts or % deviation from the nominal value. LED annunciators are provided for presignal conditions and relay operations. The regulated voltage can be lowered by means of loadshedding in 3 steps, ie, 3% , 6% and 9% of nominal voltage via external relay contacts or switches. The Auto/Manual selection allows the relay to operate in the auto mode or in the manual mode. In the manual mode, the "Raise" and "Lower" pulses are blacked, but all other alarm signalling relays are available. Load dependent voltage drops due to line impedance can be compensated by increasing/decreasing the desired value by means of simulated resistance and reactive compensation (optional). In case of failure of auxiliary supply to the relay a pair of normally closed contacts is available for signalling an alarm (Optional). The modular construction makes it very convenient for easy servicing and quick replacement of cards, without withdrawing the AVR from the control panel.