RXPDK21H 1MRK000844-BB over current relay

Overview

Place of Origin:	Sweden
Brand Name:	ABB
Model Number:	RXPDK21H  1MRK000844-BB
Packaging Details:	Original new Factory Sealed
Delivery Time:	5-7 days
Payment Terms:	T/T
Supply Ability:	In stock

Specifications

Description

The ABB RXPDK21H 1MRK000844-BB directional overcurrent relay is a high-performance industrial control device primarily used for overcurrent protection and directionality detection in power systems. It accurately identifies the direction of current, providing reliable overcurrent protection.

Applications

Substations/Plants: For directional protection of parallel feeders in high-voltage/medium-voltage distribution networks.

Thermal Power Plants: For logic interlocking protection of plant auxiliary power systems and generator leads.

Petrochemical Plants: For isolating power circuits sensitive to power supply direction in continuous production processes.

Steel Smelting Plants: For protection of power transformers and motors under high-load conditions.

Paper/Pharmaceutical Plants: For selective protection of refined power distribution systems, reducing the scope of power outages.

Common Faults

Directional Misalignment/Immovable: Usually caused by reversed polarity in the polarization voltage circuit wiring or a faulty voltage sensor (PT).

Measurement Value Drift: Analog components age after long-term operation; the start-up current (Start Value) needs to be recalibrated.

Communication Timeout: If connected to the SPA bus, check if the back-end connectors are loose.

FAQ

Q: What is the RXPDK21H 1MRK000844-BB?
A: It is a directional overcurrent relay.

Q1: Why does the RXPDK21H 1MRK000844-BB need voltage memory?
When a near-field fault causes the voltage to drop to zero, the relay cannot obtain a polarization reference. Voltage memory utilizes the voltage phase before the fault to ensure accurate triggering of the directional logic.

Q2: What does the I> scale on the RXPDK21H 1MRK000844-BB module panel represent?
It represents the starting current multiple of the Low Set Stage, used to set the threshold for inverse-time or definite-time protection.

Q3: How does the RXPDK21H 1MRK000844-BB relay achieve "directionality"?
It determines the current flow direction by comparing the current in one phase with the line voltage phase (cross-polarization) between the other two phases.

Q5: Can the RXPDK21H 1MRK000844-BB be removed while under load?
No. Direct removal may cause an open circuit on the secondary side of the current transformer (CT). It must first be short-circuited and isolated using the RTXP test switch.