How to Pair Overloads Correctly with LC1D5011 Telemecanique Replacements

Size the overload relay to the motor, not to the contactor. For a BRAH Electric replacement of the Telemecanique LC1D5011, the BLC1D5011, the catalogue lists four LR2D overload relays whose descriptions name the LC1D50: the BLR2D3353 (23 to 32 A), BLR2D3355 (30 to 40 A), BLR2D3357 (37 to 50 A) and BLR2D3359 (48 to 65 A). Pick the one whose adjustment range contains the full-load current on the motor nameplate.

The contactor and the relay do different jobs. The LC1D5011 switches the motor on and off. The overload relay watches the motor current and opens the control circuit when the motor draws too much for too long. Pairing them correctly means the relay fits the contactor, covers the motor current and is wired so that a trip drops the contactor out.

Pairing an overload with an LC1D5011: quick answer

• Start from the motor nameplate full-load current (FLA). The contactor rating does not set the relay size.
• Choose an LR2D relay that names the LC1D50 and whose range includes the FLA.
• Where two ranges overlap, prefer the relay that puts the FLA away from the ends of its dial.
• Wire the relay control contact in series with the contactor coil, and match the coil voltage of the replacement contactor to the control circuit.
• Set the dial, then prove the trip and reset before returning the motor to service.

LR2D overload relays listed for the LC1D50

The four relays below are the BRAH replacements whose catalogue descriptions name the LC1D50. The last column shows the LC1D contactors each description names; each also names the matching LC2D reversing sizes.

Each of these is described as an assembled unit with a manual reset button, complete with wiring connectors and terminals. For a motor current outside these ranges, call (855) 355-2724 with the motor nameplate details and the contactor part number. The relay table for every TeSys D and TeSys K size is in the guide to troubleshooting overload relays and choosing a replacement, and all of the relays are under overload relays.

Step 1: read the motor nameplate

Write down the full-load current at the voltage the motor is connected for, the service factor, the voltage and the horsepower. A dual-voltage motor shows two currents, so use the one for your supply. If the nameplate is unreadable, do not guess from the horsepower. Find the motor data sheet or measure the running current of a healthy motor under normal load and treat the result as a starting point only.

Then check the motor against the contactor. The catalogue lists the LC1D5011 replacement at 40HP, and its description gives 15HP at 240V, 40HP at 480V and 40HP at 600V. The 80A catalogue amperage is not a motor rating, so do not use it to size the motor or the relay. Match the contactor to the nameplate of the unit it replaces.

Step 2: choose the range that contains the motor current

Two examples using the ranges in the table:

• A motor with an FLA of 44 A falls inside 37 to 50 A, so the BLR2D3357 is the relay to look at.
• A motor with an FLA of 49 A falls inside both 37 to 50 A and 48 to 65 A. It sits at the top of one dial and the bottom of the other. Either covers the current. The choice depends on which way the setting is likely to move, so check the service factor and the rules that apply at your site before deciding.

Do not choose a relay with a range above the motor current “to stop it tripping”. A relay that cannot be set down to the motor current does not protect the motor. A relay whose range tops out below the motor current will trip in normal running.

Step 3: confirm the relay fits the replacement contactor

The BLC1D5011 is described in the catalogue as a direct substitute for the LC1D5011, and the four relays above are described as suitable for the LC1D50. Before ordering, still compare the installed pair with the product pages:

• How the relay attaches to the load side of the contactor, and whether it is mounted directly or separately.
• The position of the power terminals on both parts.
• Space below the contactor for the relay body and for the motor cables.
• Access to the dial and the reset button once the door or cover is closed.

If you are keeping the existing relay and changing only the contactor, check the relay series first. A relay with one of the four numbers in the table above is listed for this contactor size. Inspect its terminals for heat damage while it is off the contactor.

Step 4: match the contactor coil to the control circuit

The overload relay acts through the contactor coil, so the pairing only works if the coil is right. The catalogue lists the LC1D5011 replacement in these coil voltages. Every listing has 1 NO / 1 NC built-in auxiliary contacts.

If the old contactor is sound and only its coil has failed, BRAH lists LX1D6 replacement coils that name the LC1D50, for example the BLX1D6G7 (120VAC 50/60Hz). See magnetic coils.

Step 5: wire the relay into the control circuit

An overload relay does not break the motor current itself. Its normally closed control contact is wired in series with the contactor coil. When the relay trips, that contact opens, the coil loses its supply and the contactor drops out. If the relay also has a normally open contact, it can drive an alarm or indicator. Check four things:

• The normally closed contact is in the coil circuit, not bypassed.
• The terminal markings on the replacement match the drawing.
• The control voltage on that contact suits the relay.
• All three motor phases pass through the relay.

The built-in auxiliary contacts on the contactor are separate from the relay contact. For extra contacts on the contactor, BRAH lists LA1D and LA8D auxiliary contact blocks such as the BLA1DN11. For a pair of contactors used for reversing, the BLA9D50978 mechanical interlock is listed for LC1D40 through LC1D95.

Step 6: trip class and starting duty

Trip class describes how long an overload relay tolerates a heavy overcurrent, such as starting current, before it trips. Classes 10, 20 and 30 are the common ones, with the higher numbers allowing longer starts. Read the class marked on the relay you are removing and keep to it unless the motor or the driven load has changed. A fan or other high-inertia load that takes a long time to reach speed is the usual reason for a higher class. Confirm the class of the replacement on its product page or by phone before ordering.

Step 7: set the relay and test

Set the dial to the motor current as directed by the relay instructions and the electrical code that applies to the installation. Motor overload protection is covered by Article 430 of the National Electrical Code. Do not turn the setting up to cure tripping. Find the cause instead. Then test:

• Use the test function, if the relay has one, to confirm that a trip drops the contactor out.
• Press the manual reset button and confirm the contactor can be started again.
• Start the motor and measure the running current in all three phases. Compare it with the setting and the nameplate.
• Check the enclosure temperature and the terminals for heat after a period under load.
• Record the relay part number and the final setting in the maintenance log.

Common pairing mistakes

• Choosing the relay by the contactor size or by horsepower alone.
• Leaving the old setting on a new relay with a different range.
• Bypassing the relay control contact during fault-finding and forgetting to restore it.
• Ordering the contactor with the wrong coil voltage, so the starter cannot be tested at all.

Safety

De-energize the starter, apply lockout/tagout, and verify the absence of voltage on the line, load and control terminals before working on the contactor or relay. Leave setting, testing and current measurement under load to qualified personnel using equipment rated for the circuit.

About the BRAH parts

BRAH Electric is an aftermarket manufacturer and is not an authorized distributor of Telemecanique or Schneider Electric products. Its parts are designed in-house and tested at its facility in Carlsbad, California. Contactors and overload relays are covered by a 2-year warranty from the date of invoice.

LC1D5011 overload pairing FAQs

Should the overload be sized to the contactor or the motor?

To the motor. Use the full-load current on the motor nameplate. The contactor only has to be suitable for the motor and compatible with the relay.

Which overload relays go with an LC1D5011 replacement?

The catalogue lists four LR2D relays that name the LC1D50: BLR2D3353, BLR2D3355, BLR2D3357 and BLR2D3359, covering 23 to 65 A between them.

What happens if the overload range is too high?

The relay cannot be set as low as the motor current, so a sustained overload may not trip it. The motor can overheat and its insulation can be damaged.

How do I know which trip class to choose?

Match the class on the relay being replaced. Change it only if the starting time of the load calls for it and the motor is suitable.

Can I reuse the existing overload relay with a new LC1D5011 replacement?

Often, yes, if it is one of the four relays in the table, it is in good condition and its range still contains the motor current. Check the terminals and the fit to the new contactor.

Why test under load after pairing?

The test shows that a trip opens the contactor, that the relay resets, and that the running current agrees with the setting. Problems found now are cheaper than a burnt motor.

References

• NFPA 70, National Electrical Code. Article 430 covers motors, motor circuits and controllers, including motor overload protection.
• IEC 60947-4-1, Low-voltage switchgear and controlgear, Part 4-1: contactors and motor-starters, including overload relays and trip classes.
• OSHA 29 CFR 1910.147, The control of hazardous energy (lockout/tagout).
• NFPA 70E, Standard for Electrical Safety in the Workplace.