DELCO PMR 5

Overview

DELCO PMR 5 is a microprocessor-based motor protection relay manufactured by DELCO, designed for three-phase asynchronous motor protection and supervision in low-voltage motor control centers. It integrates comprehensive motor protection functions, local status indication and remote communication capability, widely supplied as exchange spare for water pump, fan, compressor and conveyor motor control cabinet overhaul and replacement.

Features

DELCO PMR 5 provides full protection coverage including overload, locked rotor, phase loss, phase imbalance, reverse phase, overvoltage, undervoltage and earth fault protection. It supports thermal memory simulation, which retains the motor thermal state after power interruption to prevent repeated start damage to hot motors. It has front segment LED indicators for power, running, pre-alarm and trip alarm, supporting fast on-site inspection.

DELCO PMR 5 supports multiple control modes: direct start, star-delta start and soft start matching. It integrates discrete input and relay output terminals for start permissive interlock, remote trip and alarm signal output. It supports Modbus RTU communication to upload motor current, thermal capacity, fault codes and running status to PLC and SCADA host systems. Trip history and thermal curve data can be read through supporting configuration software. All protection thresholds and delay parameters can be set locally via front buttons. It conforms to IEC 60947 and EMC standards for indoor cabinet mounting with IP20 rating.

Specs

DELCO PMR 5Brand: DELCO Type: digital motor protection relay Model: PMR 5 Protection items: overload, locked rotor, phase failure, phase unbalance, reverse phase, earth fault, over/undervoltage Control mode: direct-on-line, star-delta, soft-start compatible Communication: Modbus RTU Auxiliary supply: AC/DC 24V, AC110V, AC220V optional Mounting: DIN TH35 rail Protection rating: IP20 This is not a contactor, circuit breaker or VFD; it is the dedicated motor protection and monitoring relay. DELCO PMR 5 is widely supplied as service replacement spare for MCC motor protection loop failure.

Principle

DELCO PMR 5 samples three-phase current and voltage signals from external current transformers and voltage circuits. The internal microcontroller calculates the motor thermal capacity and monitors electrical abnormalities in real time. When operating value exceeds the preset threshold, the relay triggers the trip output contact, cuts off the motor control loop and locks the start command. It transmits fault information and operating data to the upper control system via Modbus RTU bus, and keeps thermal memory data until the motor cools down or manual reset.

Applications

DELCO PMR 5 is deployed for cooling water pumps, induced draft fans, air compressors, belt conveyors and general process motor circuits in water plants, power plants and chemical factories. It is selected for spare inventory and MCC cabinet retrofit projects for existing DELCO PMR series motor protection systems.