Hager HET250JR h3+ P250 3P 250 A 70 kA LSI Electronic MCCB

High-breaking-capacity electronic MCCB with adjustable LSI protection

The Hager HET250JR is an h3+ P250 moulded case circuit breaker with three poles, 250 A rated current and an electronic LSI trip unit. LSI stands for long-time (overload), short-time and instantaneous protection, each adjustable. With an ultimate breaking capacity of 70 kA at 400 V and 415 V AC and 85 kA at 230 to 240 V AC, it is aimed at boards with high prospective fault levels, for example close to transformers or generators.

It is a fixed, front-connected toggle breaker for operational voltages from 220 to 690 V, suitable for distribution boards, with copper or aluminium cable.

Technical specifications

How the LSI settings are used

The long-time dial Ir1 sets the overload pickup between 90 and 250 A, which lets the breaker be matched to a cable smaller than its frame rating. The delay tr, from 0.5 s to 16 s, sets how long an overload is tolerated, for instance to ride through motor starting. Short-time protection adds a pickup between 1.5 and 10 times Ir with a deliberate delay of 50 to 400 ms, which helps selectivity with downstream breakers. The instantaneous setting then clears heavy faults without delay.

Selection notes

Confirm the prospective fault level at the busbar against the 70 kA rating at 400 V and the lower 50 kA service rating, and check discrimination with the upstream and downstream devices using Hager’s coordination tables. The breaker has no neutral pole; a four-pole variant is needed where the neutral must be switched or protected. Add the 45 W loss to the enclosure heat balance.

How the Hager HET250JR electronic MCCB works

A moulded case circuit breaker protects a circuit from overload and short circuit and also switches it on and off. In an electronic breaker, current sensors measure the current in each pole, and a microprocessor compares it with the settings made on the trip unit. If an overload lasts longer than the delay set, the breaker trips. If the current rises to the short-time level, it trips after a short deliberate delay, and if it reaches the instantaneous level it trips at once. This LSI characteristic stands for long-time, short-time and instantaneous protection.

The advantage over a thermal-magnetic breaker is the fine adjustment, which lets the protection fit the load and coordinate with other devices in the board.

Where the HET250JR is used

• Main and sub-distribution boards in industrial plants and large buildings.
• Feeders for motors, pumps and process lines.
• Boards close to transformers or generators with high prospective fault levels.
• Systems that need selectivity between upstream and downstream breakers.

Selection checklist for the HET250JR

• Load current and cable size, with the long-time dial set between 90 and 250 A.
• Prospective short-circuit current at the board, compared with 70 kA at 400 V and 415 V AC.
• Number of poles: three poles without neutral.
• Settings required: long-time delay of 0.5 to 16 s, short-time pickup of 1.5 to 10 times Ir with delays up to 400 ms, and instantaneous levels from 3 to 11.
• Cable size from 35 to 185 mm2 rigid, copper or aluminium.
• Mounting: fixed, front connected, with accessories to be ordered separately.
• Operating temperature range from -25 to 70 degrees C and derating at high temperature.
• Space in the board, with the dimensions of 165 x 105 x 97 mm and power dissipation of 45 W at rated current.

Installation, commissioning and maintenance notes

Torque the terminals to 12 Nm, and use cable lugs and conductors suitable for the current. Set the dials to the values from the protection study, and record them in the board documents. Test the settings and the trip function at commissioning, using the method recommended by the manufacturer. Inspect the board for heat marks, dust and loose connections on a regular schedule, and operate the breaker from time to time so the mechanism does not stick. After a trip by a short circuit, find the cause and inspect the breaker before closing it again.

Requesting a quotation for the Hager HET250JR

Send the order code, quantity, fault level and any accessories such as terminal covers or auxiliary contacts. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Selectivity with downstream devices

To achieve selectivity, the upstream breaker should stay closed while a downstream device clears a fault. The adjustable short-time delay of this breaker allows that, and a selectivity table or a protection study should confirm the settings before commissioning.

Records and settings documentation

After commissioning, keep a record of the dial settings, the protection study and the test results with the board drawings. This helps maintenance teams confirm settings after any change and supports later audits of the electrical installation.

Documents and quotation

The datasheet attached here lists every setting range. Send the order code, system voltage, fault level, required protection settings and quantity with your enquiry. Related devices are in the circuit breakers category.