Guodian Nanzi PSL641UX Line Protection and Control Device

1 Overview
1.1 Scope of Application
The PSL 641UX line protection and control device is configured with current and voltage protection as its basic setup, while integrating various measurement and control functions. It is suitable for distribution lines with voltage levels of 66kV and below. Its application areas cover industries such as power, water conservancy, transportation, petroleum, chemical, coal, and metallurgy.
1.2 Protection Function Configuration
a) Three-stage directional overcurrent protection with voltage restraint
b) Two-stage directional zero-sequence protection and zero-sequence alarm
c) Overcurrent acceleration protection and zero-sequence acceleration protection
d) Overload protection (alarm or trip optional)
e) Under-frequency load shedding function
f) Under-voltage load shedding function
g) Three-phase auto-reclosing function
h) Small current grounding line selection function
i) TV disconnection detection
1.3 Measurement and Control Function Configuration
a) Measurement quantities such as current, voltage, power, power factor, etc.
b) 14 external switch input telemetry acquisition (up to 20 optional)
c) Circuit breaker position, manual tripping, and accident telemetry
d) Remote control of normal circuit breaker opening and closing
e) GPS time synchronization input

2 Protection Functions and Principles
2.1 Phase-to-Phase Overcurrent Protection
When the device performs three-stage overcurrent discrimination, the discrimination logic for each stage is consistent. The operating conditions are as follows:
1) Iφ > Idn; where Idn is the n-stage current setting value, and Iφ is the phase current;
2) T > Tdn; where Tdn is the n-stage time delay setting value.
2.1.1 Phase-to-Phase Directional Element
Adopts a 90° wiring method and operates per phase. With current flowing out of the busbar as the positive direction, the operating range is Arg(U/I) = -90° to +30°, with an error < ±5°.
2.1.2 Under-Voltage Blocking Element
The under-voltage element operates when any of the three line voltages falls below the under-voltage setting value, releasing the blocked protection element. This element ensures that the device does not malfunction under non-fault conditions such as motor feedback.