Emco EE301-T Manual

I INTRODUCTION
EMCO's Solid State Voltage Regulating Relay Type EE 301- T is used for regulating the secondary
voltage of power transformer with on-load tap changer . The required dead-band settings are set
by setting the Nominal value and L & R levels independently. The Time Delay setting on the front
panel eliminates the relay operations for momentary fluctuations of the regulated voltage, thus
reducing the number of operations of the tap changer.
When the regulated voltage falls below the specified Under Voltage limit, the control relays are
automatically blocked i.e. there is no voltage correction, and a pair of relay contacts is made
available for alarm.
When the regulated voltage goes above the specified Over Voltage limit, the control relays are
automatically blocked i.e. there is no voltage correction, and the same pair of relay contacts (for
UV) is made available for alarm.
A built-in Tap Position Indicator with 1KW step resistance can be provided optionally to indicate
the Tap No. of the Power Transformer upto a maximum of 35.
The relay uses all solid state circuitry which increases its reliability and life. The output, input
connections are made through a terminal block. However all normal precautions/care in handling/
storage should be observed as for a sensitive electronic instrument.
II GENERAL DESCRIPTION
EMCO's Solid State Automatic Voltage Regulating Relay Type EE301-T is designed for maximum
operational simplicity. It regulates the secondary voltage of power transformers with on-load
tapchangers. The bandwidth control allows the dead-band to be set in terms of upper (LOWER
VOLTS)and lower (RAISE VOLTS) voltage limits around a particular nominal value with specified
sensitivity.
The Time Delay control allows the regulator to respond only to voltage fluctuations lasting for
periods greater than the selected time delay. Where the voltage correction requires more than one
tap change, the time delay is re-initiated before further tap changes. No special provisions are
required to reset the time delay which resets automatically after the voltage correction. Solid State
Lamps (LEDs) indicate voltage outside the preset limits and control relay operations.
Operation of the RAISE / LOWER Control Relay is automatically inhibited when the voltage falls
below the specified undervoltage limit or goes above the Overvoltage limit. One pair of normally
open relay contacts are provided to effect the tapchanger RAISE and LOWER operations and to
trigger an alarm in case of Undervoltage / Overvoltage conditions. (Only one pair of contacts is
available for either UV or OV)
An alarm in the form of normally open contacts is provided in case of control failure i.e. AVR Relay
continuously showing either 'L' or 'R' command for more than 15 minutes due to malfunctioning of
AVR/OLTC/ any reason.
A built-in Tap Position Indicator with 1KW step resistance can be provided optionally to indicate
the Tap No. of the Power Transformer upto a maximum of 35.
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