2 INTRODUCTION
2.1 Features
The P153 is a four element (phase A, B, C, N) non-directional overcurrent and earth fault relay with its
functions designed to cover a wide range of applications in the protection of cables and overhead lines
deployed in industrial installations, public distribution networks, and other substations.
The P153 is an economical choice, designed for deployment in volume, in lower voltage systems, in
industrial installations and distribution network substations. P153 can also be applied for direct
refurbishment of substations using older generations of non-communicating overcurrent relays.
The principal protection functions in the relay are timed and instantaneous phase and earth fault
protection, with up to 3 independent stages available. IEC and IEEE curve types are provided for
IDMT functions. Additional versatility is provided thanks to the inclusion of negative sequence
overcurrent, thermal overload, cold load pickup, inrush blocking, broken conductor, breaker fail,
restricted earth fault, undercurrent/loss of load, and trip circuit supervision functions. Multiple setting
groups are included. The hardware capability is broadened by offering minimum ordering options to
permit standardisation in procurement and inventories.
The user may assign any of the logical/physical statuses to binary inputs, binary outputs and
programmable LEDs. This provides flexibility to program the relay as per the application requirements.
All the output contacts are changeover type for ease of implementing the desired wiring schematic.
The P153 offers supervision functions including measurement, monitoring and recording. Industry and
utility protocols such as MODBUS and IEC 60870-5-103 are available for transmitting relay data to a
supervisory control system via communication networks. The intuitive operator interface facilitates
easy reading of measured values and simple configuration of the relay.
2.1.1 Protection & Control
• Timed and instantaneous phase and earth fault protection (3 independent stages)
• Wide range of IEC/IEEE curves
• Thermal overload
• Cold load pickup
• Inrush blocking
• Undercurrent/Loss of load detection
• Negative sequence overcurrent
• Broken conductor
• Circuit breaker Fail
• Trip circuit supervision
• 4 Digital inputs
• 4 Digital output (2 NO + 2 NC)
• 1A/5A CTs selection
• Latching of output contacts
• Two power supply ranges
• 2 Setting groups