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Transparent thermal unit FH21 with current range markings

Eaton

Eaton FH21 Thermal Unit 1.72 to 1.89 A

SKU CH-QD70-XJYHJ

Thermal overload unit for NEMA sizes 0, 1 and 2, covering 1.72 to 1.89 A with Trip Class 20 protection

  • TypeIndustrial Electrical Controls & Automation
  • ColorTransparent
  • Trip Class 20 provides reliable motor overload protection
  • Full-load current range 1.48 to 1.62 A covers multiple applications
  • Extended range 1.72 to 1.87 A adds flexibility for NEMA sizes 0, 1, 2
  • Compatible with Series A200 and B100 starters simplifies integration
  • Transparent housing allows quick visual inspection of thermal element

Eaton FH21 Thermal Unit

The Eaton FH21 is a thermal overload unit calibrated for a full-load current range of 1.72 to 1.89 A. It carries a Trip Class 20 rating and fits NEMA Size 0, 1 and 2 starters. The transparent housing allows visual inspection of the internal mechanism. It is designed for industrial motor protection panels.

Suited for maintenance on Series A200

Electricians replacing a tripped heater element in a compatible starter will find the correct calibration here. The unit matches Grainger references 11Z488 through 11Z497 for direct cross-reference. Installers working with NEMA Size 3 or larger starters, or those requiring a different trip class, must select an alternative part.

Calibrated range 1.72 to 1.89 A

This specific current window is the decisive specification; the starter’s nameplate full-load amps must fall within it for proper overload protection. Using a unit outside this range will cause nuisance tripping or leave the motor unprotected. Verify the motor nameplate value before ordering.

Highlights

  • Trip Class 20 provides reliable motor overload protection
  • Full-load current range 1.48 to 1.62 A covers multiple applications
  • Extended range 1.72 to 1.87 A adds flexibility for NEMA sizes 0, 1, 2
  • Compatible with Series A200 and B100 starters simplifies integration
  • Transparent housing allows quick visual inspection of thermal element

Specifications

BrandEaton
TypeIndustrial Electrical Controls & Automation
ColorTransparent

Questions about this item

Does the FH21 thermal unit generate noticeable heat or noise when protecting a motor at 1.72 to 1.89 A all day?

The thermal unit operates passively without fans or active cooling, so it produces no audible noise and only minimal heat during continuous overload protection at its rated current range.

Which Eaton motor starters or overload relays must I already own for this FH21 unit to work?

The FH21 is compatible with Series A200 and B100 starters in NEMA sizes 0, 1 and 2, so one of those starters must be installed for the thermal unit to function.

Will the FH21 thermal unit fit older Eaton Cutler-Hammer starters that use Grainger part numbers 11Z488 through 11Z497?

Yes, the unit is listed as compatible with Grainger part numbers 11Z488, 11Z489, 11Z49, 11Z491, 11Z492, 11Z493, 11Z494, 11Z495, 11Z496 and 11Z497, covering those legacy starters.

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