Multi-function Analog Protector Relays

Rish Relay 252-PAx – AC Current Relay

The Rishabh 252-PAx continuously monitors AC current in the circuit. When the measured current exceeds the user-defined set point, the relay activates. An adjustable time delay prevents false tripping due to short-term fluctuations, ensuring stable and accurate protection.

Features

• Adjustable setpoint, time delay. Internal differential ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping. Auto Reset

Applications

• Over/ Under current. Load detection. Monitoring of electric heating systems
• General application – for any electrical load, monitoring for under-load and over-load conditions
• Motors – monitoring for conditions such as overload, locked rotor, and short circuit.
• Gensets – to ensure load current is within generator capacity.
• Machinery – detecting broken drive belts on machinery.

Rish Relay 253-PVx – AC Voltage Protection Relay with Adjustable Differential

The 253-PVx relay continuously monitors AC voltage levels. When the voltage exceeds or falls below the user-defined setpoint, the relay activates to trigger an alarm or control signal, ensuring timely response to abnormal voltage conditions.

Features

• Adjustable setpoint. Adjustable differential. Internal differential ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping. Auto Reset

Applications
Ideal for protecting against under/over voltage in systems such as standby generators, mains failure units, hybrid supplies, UPS, gensets, motors, and sensitive electronic equipment.

On request, the relay can be configured with swapped energize/de-energize logic.

Rish Relay 252-PDx – DC Voltage Protection Relay

The 252-PDx relay continuously monitors DC voltage. When the voltage exceeds or drops below the setpoint limits, the relay activates after a configurable time delay or differential, triggering an alarm and/or control signal.

Features

• Adjustable Setpoint. Adjustable time delay. Internal differential (factory settable)
• LED trip indication. 2 pole relay contacts. Adjustable Differential (252 PDE only)
• Internal time delay (252 PDE only). Auto Reset

Applications

• Under-voltage and over-voltage protection
• Battery level monitoring – LED indicates when the relay is energized
• Battery supplies – Monitors terminal voltage to detect under/over-voltage conditions
• Battery chargers – Ensures correct charging voltage

Rish Relay 252-PVx – AC Voltage Relay with Adjustable Time Delay

The 252-PVx AC voltage protector continuously monitors the circuit. If the voltage exceeds or falls below the set point limit, the relay activates after the adjustable time delay, triggering an alarm and/or initiation signal.

Features

• Adjustable setpoint. Adjustable Time Delay. Internal differential ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping. Auto Reset

Applications

• Under-voltage and over-voltage protection. Startup of standby generators

• Operation of mains failure units. Switching between hybrid or backup supplies

• Protecting computer systems. Ensuring close control of sensitive equipment

• Gensets: Monitoring AVR (automatic voltage regulator) and excitation system

• Motors: Protecting voltage-sensitive motors from overheating due to low voltage

• UPS systems: Switching to backup supply when AC voltage falls outside the acceptable range

Rish Relay 252-PHx – Frequency Relay

The 252-PHx frequency protector continuously monitors the circuit. When the frequency exceeds or falls below the set point limit, the relay activates, triggering an alarm, control, or trip signal. An illuminated LED indicates when the relay is energized.

Features

• Adjustable setpoint. Adjustable differential. Internal Time Delay ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping. Auto Reset

Applications

• Under speed and over speed protection. Under frequency and over frequency protection
• Standby supplies for industrial, hospital, or marine use. Mains and computer supplies
• Gensets: Monitoring engine speed controller (Governor) operation
• Motors: Ensuring correct speed for synchronous motors
• Standby supplies: Switching to alternate supply when AC frequency is outside acceptable range

Rish Relay 252-Pxx – Millivolt / Thermocouple Relay

The 252-Pxx relay accepts DC millivolt inputs from shunts, transducers, or standard thermocouples. It features user-adjustable trip points and time delay settings, typically from 0 to 10 seconds, with longer delays available on request.

Features

• Adjustable setpoint. Adjustable Time delay. Internal differential ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping
• Supports all industry standard shunts and popular thermocouples. Auto Reset

Applications

• Using Current Shunts: Detect current drain. Under/overcurrent protection.
• Using Thermocouples: Monitor battery charging current. Under/overtemperature protection. Hotspot detection.

Rish Relay 256-PHV – Combined Under/Over Voltage & Frequency Relay

The 256-PHV provides continuous monitoring of both voltage and frequency. It features user-adjustable trip points and time delay settings for precise protection against abnormal power conditions.

Features

• Adjustable setpoint. Adjustable Time Delay. Internal differential ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping. Auto Reset

Applications: 

• Protection against over/under frequency and over/under speed
• Overvoltage and undervoltage protection
• Gensets: Monitor AVR, excitation system, and engine speed (Governor)
• Motors: Ensure correct speed and prevent overheating in voltage-sensitive or synchronous motors
• UPS systems: Trigger switch to backup supply when voltage or frequency goes out of range

Rish Relay 252-PSx – Phase Balance Relay

The 252-PSx de-energizes the output relay when a phase imbalance or fault is detected. It features an adjustable time delay to avoid false trips from brief fluctuations. A red LED indicates normal operation and an energized relay.

Features

• Adjustable set point. Adjustable time delay. Internal Differential
• LED trip indication. 2 pole relay contacts. Auto Reset

Applications:

• Protects motors from overheating caused by unbalanced phases (e.g., 10% imbalance can raise temperature by 150%)
• Detects regenerated voltage during single-phase failure at low loads
• Suitable for: Portable pumps and compressors. Motors (single phasing protection). Gensets (ensures correct engine rotation). All portable equipment and rotating machines

Rish Relay 256-PAx – Reverse Power Relay

The 256-PAx continuously monitors AC generators running in parallel or boosting mains supply. It offers on-site adjustable trip point and time delay for precise reverse power protection.

Features

• Adjustable set point. Adjustable time delay. LED trip indication
• 2 pole relay contacts. Internal Differential (factory settable only). Auto Reset

Applications:

• Continuous monitoring of AC generators operating in parallel or boosting mains supply
• Protects against reverse power and “motoring” in case of engine failure
• On-site adjustable trip point and delay for precise synchronizing without false trips
• Generator sets: Detects engine loss and prevents reverse power flow
• Feeders: Identifies reverse power under fault conditions

Rish Relay 252-PVR – Phase Sequence & Phase Failure Relay

The 252-PVR is designed to monitor the correct phase rotation (L1, L2, L3) in 3-phase systems. It protects rotating machines from damage caused by incorrect phase sequence or phase loss.

Features

• LED trip indication. 2 pole relay contacts. Auto Reset

Applications: 

• Portable pumps, compressors, and mixing equipment
• Motor protection against single phasing
• Gensets: Ensure correct engine rotation
• All rotating and portable electrical machines
• Protection against incorrect phase sequence and phase loss
• LED indication shows relay status

Rish Relay 252-PMx – Thermistor Trip Relay

The 252-PMx relay de-energizes when thermistors in a motor stator detect abnormal temperature conditions. A green LED illuminates to indicate that the temperature is within normal working limits.

Features

• LED trip indication. 2 pole relay contacts
• Energize/De-energize function swapping. Auto / Manual Reset

Applications:

• The Thermistor Trip Relay, when used with positive temperature coefficient thermistors, protects against: Sustained overload. Single phasing. Locked rotor. Blocked ventilation. High ambient temperature

Rish Relay 25x-PBx – Transducer Trip Relay

The 25x-PBx accepts analog signals (DC voltage or current) from most measuring transducers and transmitters. It monitors inputs within preset limits and triggers an action if the input moves outside these limits.

Features

• Adjustable setpoint Adjustable Time delay. Internal differential ( factory Settable )
• LED trip indication. 2 pole relay contacts. Energize/De-energize function swapping. Auto Reset

Applications:

• Forward / Reverse Watts.  Forward / Reverse VAr
• Under / Over Watts. Under / Over VAr. Under / Over VA
• Power Factor Monitoring And Control

Rish Relay 256 PRx – Hot-Spot 3 Relay

The 256 PRx temperature trip relay monitors three separate temperature zones in large electric motors, transformer windings, or any temperature-sensitive equipment, including process lines, gas turbines, and engine-driven generators, using Resistance Temperature Detectors (RTDs).

Features

• Up to three RTD inputs. 1mA analogue output. Three adjustable set points. Internal differential.
• LED trip indication. Automatic reset. Three single-pole relay contacts

Applications: 

• Motor protection. Transformer protection. Gensets protection
• Heating equipment protection. Ineffective cooling. Blocked ventilation
• Overloads. Worn bearings

Rish Relay 256-PLx – Synchro-check Relay

The Synchro-check relay aids in the semi-automatic paralleling of two AC power systems. The Rishabh Paralleling Protector ensures safe manual or automatic switching of the generator to the busbar, preventing system damage or disturbances.

Features

• LED trip indication. Two pole relay contacts (optional)
• Adjustable synchronizing set points. Live and Dead bus versions

Applications:

• Co-generation. Generator sets. Gen-Bus synchronizing. Bus-Bus synchronizing
• Assists in manual synchronizing. Monitors auto-synchronizing systems

Rish Relay 256-PCC – Hot-Spot 6 Relay

The Hot-Spot 6 is a temperature trip relay that accepts up to six inputs from Resistance Temperature Detectors (RTDs). The temperature trip point, shared across all six channels, is user-adjustable.

Features

• Up to six RTD inputs. Adjustable set point. Internal differential
• LED trip indication. Auto reset

Applications:

• Motor protection. Transformer protection. Gensets protection
• Heating equipments protection and the protection against
• Ineffective cooling. Blocked ventilation
• Overloads. Worn bearings. Locked rotor

Rish Relay 253-EFR – Earth Fault Relay

The 253-EFR is equipped with adjustable earth fault current trip settings and time delay. The relay energizes when a fault is detected. It supports external CTs with a 5 A or 1 A secondary rating, selectable via terminals 1 & 2 or 1 & 3.

Features

• Earth leakage detection with adjustable sensitivity. User-settable earth fault percentage and trip delay. Test simulation function. Manual and remote reset options
• LED indicators for power and trip status. 2-pole relay contacts
• Durable polycarbonate housing (UL 94 V-0). Transparent protective terminal cover (UL 94 V-0)

Applications: 

• Earth fault monitoring in low- and medium-voltage systems
• Protection for power distribution boards
• Integration in generator and transformer panels
• Enhanced safety for critical industrial equipment

Rish Relay 253-MPR – Motor Protection Relay

The 253-MPR relay is engineered to monitor the phase sequence (R-Y-B) in three-phase systems, ensuring correct phase rotation. It provides reliable protection for motors and rotating equipment, which are especially sensitive to incorrect phase sequencing that can lead to malfunction or damage.

Features

• Phase Sequence. Phase Loss. Adjustable unbalance Voltage. Testing Simulation
• Automatic, manual & remote reset available. LED indication for Trip & Power ON
• 2 pole relay contacts. Polycarbonate casing (UL 94 V-0). Protective clear terminal cover (UL 94 V-0)

Applications:

• Portable pumps. Portable compressors
• Motor driven mixing equipment. Motors
• Gensets – correct engine rotation. All portable motorised equipment. All rotating machines