Specifications

PIP ELCGL01
November 2002 Electrical Design Criteria
Process Industry Practices Page 7 of 20
3.4 Utility Interface Parameters
Utility interface parameters shall be as specified on the Data Sheet.
3.5 System Parameters
System voltage levels, motor hp range for each voltage level, and system grounding
methods shall be as specified on the Data Sheet. System voltages shall be within the
tolerances as set forth in IEEE 141-1993, Chapter 3, unless modified otherwise as
shown below in Section 3.6.
3.6 Steady State Voltage
3.6.1 Voltage drop from the substation bus to the loads supplied from the
substation shall not exceed 5%, typically split as 2% feeder and 3% branch
circuit.
3.6.2 Transformer secondary side no-load voltage shall rise no more than 8%
above the nominal system voltage at the transformer secondary terminals.
3.7 Motor-Starting Voltage Drop
3.7.1 Motor-starting conditions shall be evaluated based on system and process
conditions that result in the minimum motor acceleration torque.
3.7.2 Acceleration studies shall be made for motors 250 hp and larger, unless
otherwise specified on the Data Sheet. Acceleration studies shall assure
adequate motor acceleration torque and acceptable system voltage drops for
defined system configurations and defined process conditions. Refer to
PIP ELSMT03.
3.7.3 For motors of ≤600-volt rating, the system shall be designed to provide, as a
minimum, 90% nominal system voltage at the substation bus during starting
unless specified otherwise on the Data Sheet.
3.7.4 For motors of ≤600-volt rating, the system shall be designed to provide, as a
minimum, 85% of nominal motor-rated terminal voltage at the motor
terminals during starting.
3.7.5 For motors of ≤600-volt rating that cannot be started across the line,
electronic soft starters shall be used unless specified otherwise on the Data
Sheet.
3.7.6 For motors of >600-volt rating, the system shall be designed to provide, as a
minimum, 85% nominal system voltage at the substation bus during starting
unless specified otherwise on the Data Sheet.
3.7.7 For motors of >600-volt rating, the system shall be designed to provide, as a
minimum, 80% of system nominal voltage at the motor terminals during
starting unless specified otherwise on the Data Sheet.
3.7.8 For motors of >600-volt rating that cannot be started across the line because
of system voltage drop requirements, a captive transformer shall be used
unless specified otherwise on the Data Sheet.