Phase Loss Relays | McMaster-Carr

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16 Products

Smart Multifunction Monitoring Relays

Remotely control these relays through an app on your smartphone—they simultaneously monitor phase, voltage, and frequency. The downloadable app lets you change the tripping range, modify settings, and save programs to apply to multiple relays. Tap your smartphone or tablet to the relays to connect to them. They use NFC (near field communication), so you don’t need to manually pair them like Bluetooth devices.

You’ll often see these relays used to protect motors, generators, and other three-phase circuits from burning out or overheating. They'll switch the circuit off if they detect voltage or frequencies outside of the set range or phase loss, imbalance, or reversal. You can see that they're wired correctly and when they're actuated based on the LED indicators. Rated IP20, they have recessed terminals that keep fingers and other objects from touching live circuits. Mount them on a 35 mm DIN rail (also known as DIN 3 rail) for fast installation.

	Input Freq., Hz	Trip Freq., Hz	Trip Time, sec.	Reset Type	Switching Current @ Voltage	Max. Switching Voltage, V AC	Ht.	Wd.	Dp.	Operating System Compatibility		Each
2 Circuits Controlled with 2 Off or 2 On—DPDT







	With Screw Terminals

	12	208, 240, 300, 480	208 to 480	50, 60	45 to 66	0.1 to 60	Automatic	8 amp @ 240V AC	250	3.5"	0.9"	3.9"	Android 7.0 or Later, iOS 14.5 or Later	8452N11	0000000

Surface-Mount Motor Voltage Monitors

Protect electric motors from phase loss, phase reversal, overvoltage, undervoltage, and voltage imbalance. Also known as voltage-monitoring relays, these monitors cut power to a motor when a fault occurs.

					Trip Time, sec.		Switching
	Input Voltage Range, V AC	No. of Terminals	Control Power, W	Voltage Imbalance Adjustment	Automatic Reset	Delayed Automatic Reset	Current, amp	Voltage, V AC	Ht.	Wd.	Certification		Each
1 Circuit Controlled with 1 Off or 1 On—SPDT







				For Three Phase

				190 to 480	7	6	2% to 8%	1 to 30	1 to 500	10	240	3.5"	2.08"	UL Listed	7632K72	0000000


				475 to 600	7	6	2% to 8%	1 to 30	1 to 500	10	240	3.5"	2.08"	UL Listed	7632K74	000000

Motor Starter Overload Protectors

Upgrade motor starters that use thermal overload protection with these solid-state overloads—they don't use heating elements, so enclosure ventilation and cooling is not required. All have a full-load amp adjustment dial to accommodate circuits with different full-load amp ratings.

If the full-load amp rating is not shown on your motor’s faceplate, estimate the current rating (given the motor’s horsepower and voltage).

	Motor Protection	Ht.	Wd.	Dp.	Wire Connection	Certification		Each
2 Auxiliary Contacts with 1 Off, 1 On







	For Single Phase

	3 to 12	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.2"	3.5"	3.2"	Screw Terminal	UL Listed, CSA Certified	7730K53	0000000


	5.5 to 22	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.2"	3.5"	3.2"	Screw Terminal	UL Listed, CSA Certified	7730K54	000000




			For Three Phase

			0.75 to 3.4	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	3.2"	3.5"	3.2"	Screw Terminal	UL Listed, CSA Certified	7730K62	000000


			3 to 12	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.2"	3.5"	3.2"	Screw Terminal	UL Listed, CSA Certified	7730K63	000000
			5.5 to 22	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.2"	3.5"	3.2"	Screw Terminal	UL Listed, CSA Certified	7730K64	000000
			10 to 40	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.2"	3.5"	3.2"	Screw Terminal	UL Listed, CSA Certified	7730K65	000000
			13 to 52	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.3"	4.5"	4"	Screw Terminal	UL Listed, CSA Certified	7730K66	000000
			25 to 100	5, 10, 20, 30	5, 10, 20, 30	Overvoltage, Phase Loss	2.3"	4.5"	4"	Screw Terminal	UL Listed, CSA Certified	7730K67	000000

DIN-Rail Mount Motor Voltage Monitors

Mount these monitors to 35 mm DIN rail. They protect electric motors from phase loss, phase reversal, overvoltage, undervoltage, and voltage imbalance. Also known as voltage-monitoring relays, they cut power to a motor when a fault occurs.

							Switching
	Input Voltage Range, V AC	No. of Terminals	Control Power, W	Voltage Imbalance Adjustment	Trip Time, sec.	Reset Type	Current, amp	Voltage, V AC	hp @ Voltage	Ht.	Wd.	Certification		Each
1 Circuit Controlled with 1 Off or 1 On—SPDT







				For Three Phase

				200 to 480	9	5	2% to 10%	1 to 30	Automatic	10	240	1/3 hp @ 240V AC	3"	2"	UL Listed, C-UL Listed	6969K52	0000000

Socket-Mount Motor Voltage Monitors

Plug these monitors into relay sockets for fast installation and replacement. They protect electric motors from phase loss, phase reversal, overvoltage, undervoltage, and voltage imbalance. Also known as voltage-monitoring relays, they cut power to a motor when a fault occurs.

Sockets—Relay sockets (sold separately) mount to 35 mm DIN rail or flat surfaces.

	Voltage Monitors													Sockets
							Switching
	Input Voltage Range, V AC	No. of Terminals	Control Power, W	Voltage Imbalance Adjustment	Trip Time, sec.	Reset Type	Current, amp	Voltage, V AC	Ht.	Wd.	Certification		Each		Each
1 Circuit Controlled with 1 Off or 1 On—SPDT







				For Three Phase

				200 to 480	8	5	2% to 10%	0.25 to 30	Automatic	10	240	2.4"	1.8"	UL Recognized Component, CSA Certified	6973K73	0000000	7122K26	00000

Multifunction Monitoring Relays

Monitor phase, voltage, and frequency at the same time to protect motors, generators, and other three-phase circuits from burning out or overheating. They'll switch the circuit off if they detect voltage or frequencies outside of the set range or phase loss, imbalance, or reversal. Rated IP20, they have recessed terminals that keep fingers and other objects from touching live circuits. Mount them on a 35 mm DIN rail (also known as DIN 3 rail) for fast installation.

These relays use IO Link, so they can be programmed, monitored, and reset remotely by connecting them to a programmable logic controller (PLC), human-machine interface (HMI), or computer. If you want to program them locally, they have a keypad.

Spring-Clamp-Terminal Wire Connection—Relays with spring-clamp terminals connect and disconnect to wire without screws. Because there’s no screw, these connections are less likely to loosen over time, even in high-vibration environments.

	Input Freq., Hz	Trip Freq., Hz	Trip Time, sec.	Reset Type	Switching Current @ Voltage	Max. Switching Voltage	Adjustment Mechanism	Ht.	Wd.	Dp.		Each
1 Circuit Controlled with 1 Off or 1 On—SPDT







	Screw Terminals with IO Link

	12	24	90 to 760	50, 60	15 to 70	0.1 to 30	Automatic	3 amp @ 240V AC 1 amp @ 24V DC	400V AC 250V DC	External Controller, Keypad	3.9"	0.9"	3.6"	8449N12	0000000




			Spring-Clamp Terminals with IO Link

			12	24	90 to 760	50, 60	15 to 70	0.1 to 30	Automatic	3 amp @ 240V AC 1 amp @ 24V DC	400V AC 250V DC	External Controller, Keypad	3.9"	0.9"	3.6"	8449N11	000000