Magnet Thermal Relay 1.6 – 2.5A, 2.5 – 4A, 4 – 6A, 5.5 – 8A, 9 – 13A, 12 – 18A, 17 – 25A, 23 – 32A JR28S | High-Performance Overload Protection

Thermal relay JR28S is the practical add-on when you want a motor starter to stop before the motor cooks. A contactor can switch a motor on and off, but it does not measure whether that motor is quietly pulling too much current for too long. That is the relay’s job. On this CNC Electric Pakistan page, the listed adjustment ranges run from 1.6–2.5A up to 23–32A, with live prices starting at Rs.1,450. It suits DOL starter panels, pump controls, compressor panels, workshop machines and small industrial motor circuits where overload and phase-failure protection matter.

Key Features and Specifications

Technical Specifications

This description uses only data published on the live product page plus limited JR28S family information that helps explain how a thermal overload relay is normally selected. Exact trip class, detailed frame dimensions, and accessory-terminal detail are not currently listed on the live product page and have not been guessed.

Product Range and Models

Applications in Pakistan

A thermal overload relay earns its keep on the days when a motor is not fully failed but is clearly unhappy. That is common in Pakistan. Voltage dips, one weak phase, tight mechanical load, dust in the driven machine, and operators restarting again and again all push motor temperature upward without creating a clean short circuit. The MCB may stay on. The contactor may keep pulling in. The relay is what tells the starter to stop.

Typical examples are easy to recognize. A water pump room in Karachi may run long hours in heat and poor ventilation. A textile-side auxiliary motor in Faisalabad may start and stop through the shift with varying load. A compact workshop machine in Lahore or Sialkot may be wired through a simple contactor starter where there is no smart protection at all. In these cases, the right overload range matters more than buying the biggest relay on the page.

• Pump starter panels for bore, pressure, booster and utility water systems
• Small compressor and blower motors where overload rises gradually
• Lathe, drilling, polishing and light machine-tool duty in workshop panels
• Auxiliary motors in textile, packaging and process lines
• Commercial HVAC or ventilation starter panels where repeated start cycles are common

Sizing and Selection Guide

Choose the relay by motor full-load current, not by guesswork and not by matching only motor horsepower printed on a sticker. If the motor normally draws 6.8A, the right relay is the one whose setting window cleanly includes 6.8A. Buying a 23–32A relay for that motor just because it looks safer defeats the whole point of overload protection.

CNC vs Competitors

What This Product Does NOT Protect Against

A thermal relay is not a full protection system by itself. It does not replace a circuit breaker for short-circuit protection. It does not act as surge protection for lightning or switching spikes. It does not solve under-voltage and over-voltage problems coming from the utility side. It also does not replace a phase sequence relay where wrong phase rotation is a risk on 3-phase machinery.

That is why motor panels are usually built as a set: magnetic contactor for switching, thermal relay for overload, circuit breaker for short-circuit and upstream isolation, phase sequence relay where phase health matters, and SPD where the panel is exposed to switching surges.

Installation Guide

1. Confirm the motor full-load current from the nameplate or measured operating current.
2. Choose the JR28S range that comfortably includes that running current instead of oversizing.
3. Mount the relay correctly with the matching starter arrangement and wire it into the contactor control circuit so a trip actually drops the motor out.
4. Set the dial to the correct motor current and check reset mode before handover.
5. Test the panel after assembly. A badly set overload relay is almost as useless as having no overload relay at all.

Related Products

• Magnetic contactors — the natural partner for building DOL starters and control panels.
• Circuit breakers — needed upstream for short-circuit protection and isolation.
• Phase sequence relays — useful when reverse phase and phase loss can damage 3-phase motors.
• Push buttons — complete the start/stop side of a simple motor control station.
• Industrial products — for broader panel-building and automation hardware.
• SPD — a sensible add-on if the motor panel sits near switching equipment or unstable utility supply.
• DIN rail fire extinguisher — final add-on for enclosed starter and control panels.

Frequently Asked Questions

1) What does a thermal relay do in a motor starter?

It watches motor current over time and trips the control circuit when the motor is overloaded or a phase problem develops. That protects the motor from heating damage that a simple contactor cannot detect.

2) Can I use JR28S without a contactor?

The family is published as mountable onto contactors or as single units, but in normal motor-control practice it is most useful as part of a proper starter arrangement.

3) Does this relay protect against short circuit?

No. Use an upstream breaker or other suitable protective device for short-circuit protection. Thermal overload relays are for overload and phase-failure type conditions.

4) Which size should I buy if my motor current is 10A?

The 9–13A range is the logical starting point because it lets you set the trip close to the real operating current.

5) Why not buy the biggest relay and set it low?

Because oversizing reduces protection quality. The relay should work in the right current window, not at an unrealistic edge far from the motor’s real running current.

6) Is this useful for water pumps in Pakistan?

Yes. Pump motors are a common case for overload relays because they may suffer long running hours, ventilation problems, low voltage, or mechanical load issues.

7) Does JR28S help if one phase drops?

Yes. Phase-failure protection is one of the published family functions, which is important on 3-phase motor circuits.

8) What should I buy with this relay?

Usually a matching magnetic contactor, an upstream circuit breaker, and where needed a phase sequence relay and SPD.

JR28S is a sensible buy when your panel already has switching hardware but still needs real motor-overload protection. The live product page gives you eight current ranges from 1.6–2.5A to 23–32A, with prices from Rs.1,450 to Rs.2,150, so it is easy to match the relay to actual motor current instead of guessing. If you need help pairing it with a contactor, breaker, phase relay or SPD, contact CNC Electric Pakistan on WhatsApp 0326-1111376. Orders above Rs.10,000 qualify for free delivery.