Thermal relay 12–18A – code: TELRD21 – HP Watermakers

TELRD21 thermal relay (Schneider Electric LRD21) for HP Watermakers

The TELRD21 thermal relay is a spare part component used in systems HP Watermakers for the protection of electric motors. It is a thermal overload relay based on the component Schneider Electric LRD21 of the series TeSys Deca (LRD), designed to intervene in case of prolonged overload and in the presence of abnormal conditions such as phase imbalance/loss.

In the nautical and onboard plant engineering field, this type of protection is an integral part of the engine's command and safety chain: it helps preserve the electrical system and manage abnormal conditions in an orderly manner, interrupting the circuit when necessary.

Component features and details

Below are the available and verified information for the correct identification of the replacement and for integration into the electrical panel.

Product identification

• HP Watermakers code: TELRD21
• Manufacturer code (component): LRD21
• Component manufacturer: Schneider Electric
• Series: TeSys Deca (LRD)
• Type: thermal overload relay for motors
• Original spare part: yes

Verified technical data

• Current adjustment range: 12–18 A
• Trip class: 10A
• Rated operational voltage (Ue): up to 690 V AC
• Type of protection: bimetallic with phase imbalance detection
• Mounting: direct on contactors TeSys D (LC1D18–LC1D38)
• Connection: screw terminals
• Reset: manual or automatic selectable
• Controls: buttons Test and Reset
• Auxiliary contacts: 1 NO + 1 NC
• Width: 45 mm

Note on codes and correspondences

To avoid errors during procurement, it is advisable to always check the code on the installed component and the panel list. In this sheet, TELRD21 identifies the spare part within HP Watermakers, while LRD21 is the code of the Schneider Electric component.

Typical applications on HP Watermakers systems

In the system HP Watermakers, the TELRD21 is used for the protection of the electric motor of the pump or other engines of the system. In case of prolonged overload or malfunction, the thermal relay intervenes by interrupting the circuit, contributing to the safety management of the engine/start group.

Direct mounting on contactors TeSys D contactors allows the creation of a compact motor starter, a common solution in electrical panels where neat integration and easy maintenance are required.

Operational advantages (from a maintenance perspective)

• Identifiable and traceable replacement through dual coding (HP Watermakers and Schneider Electric).
• Integration into the panel thanks to direct mounting on the indicated TeSys D contactors.
• Intervention management and reset with selectable reset (manual or automatic) and dedicated controls (Test/Reset).
• Diagnostic support through auxiliary contacts 1 NO + 1 NC, useful for signaling or control logic.
• Practical connections with screw terminals, typical of panel installations.

Usage and important notes

The thermal relay is a protective device that requires correct setting of the adjustment range depending on the motor and the application. During replacement or maintenance:

• check the matching codes (TELRD21 / LRD21) and the series of the contactor on which it is mounted;
• check the presence and use of auxiliary contacts (1 NO + 1 NC) in the control/signaling circuit;
• evaluate the setting of the reset (manual or automatic) based on the panel logic and onboard procedures;
• use the buttons Test and Reset according to the verification and system restoration practices.

For electrical system interventions, follow safety procedures and, if necessary, rely on qualified personnel.

FAQ – Frequently Asked Questions

Are TELRD21 and LRD21 the same component?

TELRD21 is the code used in the HP Watermakers field; the component is based on the Schneider Electric thermal relay identified as LRD21. When replacing, it is good practice to check both codes on the device and in the panel documentation.

What is the adjustment range of the TELRD21 thermal relay?

The verified current adjustment range is 12–18 A. The setting must be made according to the motor and system configuration.

On which contactors can it be mounted?

Mounting is intended directly on Schneider Electric TeSys D series contactors, particularly LC1D18–LC1D38, to create a compact motor starter.

What type of reset is available?

The relay provides selectable manual or automatic reset and has dedicated Test and Reset buttons for verification and restoration operations.

Are auxiliary contacts available for signaling or control?

Yes. The relay includes auxiliary contacts 1 NO + 1 NC, usable for control and/or signaling logic depending on the panel wiring.