Condition Sensing Switches and Controls

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Temperature, Mechanical

Modifications

Ordering Modifications

Modifications are ordered by adding the appropriate modification suffix code to the catalog number of the basic device. Add suffix codes to the catalog number in descending order whenever possible (highest number first).

Contact Blocks — Trip temperature-indicating scales are supplied on controls with standard contact block.

Description	Rating	Symbol	Suffix Code
Automatic Operation
Standard contact block — Single-pole, double-throw, snap-action. Supplied when a contact block suffix is not added to the catalog number.	Control circuit rating: See Control Circuit Ratings.		—
Single-pole double-throw — slow acting contact with no snap action. Contacts close on rise and close on fall with an open circuit between contact closures.	Control circuit rating: AC-125VA, 24…250V		¬ T	X171
Single-pole single-throw, normally open — closes on rise.	0.5 Hp, 115V AC 1 Hp, 230V AC Control circuit rating: AC-125VA, 24…110V AC-345VA, 110…600V DC-57.5VA, 110…250V		¬ T	X221
Single-pole single-throw, normally closed — opens on rise.			¬ T	X231
Single-pole single-throw, normally open — closes on rise.	1 Hp, 115V AC 1.5 Hp, 230V AC Control circuit rating: AC-600VA, 110…600V DC-57.5VA, 110…250V		¬ T	X321
Single-pole single-throw, normally closed — opens on rise.			¬ T	X331
External Manual Reset‡
Single-pole single-throw, normally open — contacts open at a predetermined setting on fall and remain open until system is restored to normal run conditions, at which time contacts can be manually reset.	Non-inductive: 5 A, 240V 3 A, 600V Control circuit rating: AC-125VA, 24…600V DC-57.5VA, 115…230V		¬ ‡ § §	X140
Single-pole single-throw, normally closed — contacts open on rise and remain open until system is restored to normal run conditions, at which time contacts can be manually reset.			¬ ‡ § §	X150
Single-pole double-throw, one contact normally closed — contact opens on rise and remains open until system is restored to normal run conditions, at which time contact can be manually reset. A second contact closes when the first contact opens.			¬ ‡ § §	X15A
¬ Contact blocks not available for field conversion or replacement.
T Minimum specified differential value approximately doubles.
‡ Manual reset devices cannot be supplied with an adjustable differential. Differential is approximately three times the minimum published differential of the corresponding adjustable differential control. Not available on Type 4X enclosed devices.
§ Available only for replacement of complete open type control in an existing Type 1 or 4 & 13 enclosure. Replacement in a Type 7 & 9 enclosure is not available because it would void UL and CSA.
§ Type 7 & 9 enclosures for manual reset devices are not also rated Type 4 & 13.
Note:NEMA does not rate contacts to switch low voltage and current. Bulletin 837 Styles A, H, and V temperature controls are supplied with silver contacts. The devices are designed to deliver high force snap action to the contacts. This provides exceptional contact fidelity at 24V DC I/O card current level entry when the integrity of the enclosure is maintained.

Modifications are ordered by adding the appropriate modification suffix code to the catalog number of the basic device. Add suffix codes to the catalog number in descending order whenever possible (highest number first).

Modifications

Tamper-Resistant Adjustment

Modification	Description	Suffix Code
Tamper-resistant adjustment	Range and differential adjustment screws are designed so that after a setting has been applied to the control, the adjustment screws can be broken off with a pliers. Modification does not include factory setting charge. Note: The “break-off” adjustment screw(s) will not be broken off unless a factory setting is given and the order specifies “Break off Adjustment Screw(s)”. See Factory-Set Temperature Controls.	X4
Neon pilot light 120V AC	A high-intensity neon pilot light is available for 120V AC, 60 Hz applications and can be wired for ON or OFF operation. The current rating is 1.0 mA.¬	X9
Red LED pilot light 24V DC	A high-intensity LED 24V DC pilot light is available to meet the requirements of the automotive, machine tool builders, and other industries. The current rating is 22 mA and can be wired for ON or OFF operation.¬	X15
Green LED pilot light 24V DC		X18
Armored capillary	Added capillary protection for copper alloy bulb and capillary type temperature controls. Supplied with bronze armor. For use on Cat. Nos. 837-A2…837-A7 only.	X706
	Added capillary protection for stainless steel bulb and capillary type temperature controls. Supplied with stainless steel armor. For use on Cat. Nos. 837-A60…837-A62 only.	X906
Manual test button	Allows electrical testing of circuit. See Style H — Direct Horizontal Immersion¬ T . Not available for all contact blocks.	X47
5-Pin mini-type receptacle no pilot light	Supplied with receptacle ready for field wiring.T	X42
5-Pin mini-type receptacle with pilot light	Supplied with receptacle and pilot light ready for field wiring. Pilot light suffix code X9 (120V AC Neon), suffix code X15 or X18 (24V DC LED) must also be specified. See suffix code X9, X15 or X18 description above.T	X43
5-Pin micro-type receptacle no pilot light	Supplied with receptacle ready for field wiring.T	X142
5-Pin micro-type receptacle with pilot light	Supplied with receptacle and pilot light ready for field wiring. Pilot light suffix code X9 (120V AC Neon) or suffix code X15 or X18 (24V DC LED) must also be specified. See suffix code X9, X15 or X18 description above.T	X143
¬ Not available on combined Type 7 & 9 and 4 & 13, Type 4X, and manual reset devices.
T Not available for combined Type 7 & 9 and 4 & 13 or Type 4X enclosures.