WESTINGHOUSE E-Series MCCB (Molded Case Circuit Breaker)

ESK 36kA Adjustable Thermal Magnetic Release (TM) Thermal Release 0.8-1.0In, Magnetic Release 5-10In, Flexible Adaptation  320A、400A、500A、630A ESK3320TM（W605890） ESK4630TM（W605909）

ESK 36kA Electronic Release (E) Electronic Adjustment, High Accuracy, Stable Protection Characteristics 500A, 630A ESK3500E (W607452) ESK4630E (W610439)

EHK 50kA Adjustable Thermal Magnetic Release (TM) High Breaking Capacity+Adjustable Parameters, Suitable for Large Equipment Power Distribution  320A、400A、500A、630A EHK3320TM（W605894） EHK4630TM（W605913）

EHK 50kA electronic release (E) high breaking and high-precision electronic release, suitable for precision industrial systems  500A、630A EHK3500E（W607454） EHK4630E（W610441）

ESKY - Non Automatic Manual Control, No Automatic Protection, Suitable for Special Control Scenarios  320A、400A、500A、630A ESKY3320（W605898） ESKY4630（W605917）

Types and protection characteristics of trip units

The trip unit is the core of the circuit breaker, responsible for detecting circuit abnormalities and triggering tripping. The E series provides three types of trips to meet different precision and scenario requirements, and the protection characteristics are clearly defined by the time current curve:

（1） Detailed explanation of types of trip units

Fixed Thermal&Magnetic Release

Working principle: The thermal trip element (bimetallic strip) detects overload current, slowly heats up and deforms to trigger tripping (delayed protection); Magnetic release element (electromagnet) detects short-circuit current and instantly generates suction force to trigger tripping (instantaneous protection).

Advantages: Simple structure, high reliability, low cost, no need for power supply, suitable for general scenarios without special adjustment requirements for paired protection parameters.

Adjustable Thermal&Magnetic Release

Adjustment range: Thermal trip (overload protection) 0.8-1.0In, the overload threshold can be fine tuned according to the circuit load characteristics; Magnetic release (short-circuit protection) 5-10In, adaptable to different short-circuit current levels.

Advantages: Strong universality, able to flexibly match different load types (such as motors, lighting, power equipment), and is the main release type of the E series.

Electronic Adjustable Release

Core features: By detecting current through electronic components, the adjustment accuracy is higher (with an error of ± 2%), and the protection characteristics can be subdivided (such as long delay, short delay, instantaneous), only available in EK frame 500-630A models.

Advantages: More comprehensive protection functions, suitable for precision equipment and industrial automation systems with high protection accuracy requirements.

（2） Time current curve characteristics

Circuit breakers of different current levels have clear time current curves to ensure the accuracy and coordination of protection actions:

EJ framework 200-250A (ESJ, EHJ series):

Overload protection (delay): When the rated current is 1.3 times, the tripping time is about 10-30 minutes; When the rated current is 4 times, the tripping time is about 2-6 minutes.

Short circuit protection (instantaneous): maximum instantaneous tripping current 2500 ± 500A, total breaking time ≤ 0.05 seconds.

EK framework 315-400A (ESK, EHK series):

Overload protection (delay): When the rated current is 1.3 times, the tripping time is about 14-30 minutes; When the rated current is 6 times, the tripping time is about 4-10 minutes.

Short circuit protection (instantaneous): instantaneous tripping current 6-10In (± 20%), total breaking time ≤ 0.05 seconds.

EK frame 500-630A (ESK, EHK series):

Overload protection (delay): When the rated current is 1.3 times, the tripping time is about 14-30 minutes; When the rated current is 6 times, the tripping time is about 4-10 minutes.

Short circuit protection (instantaneous): instantaneous tripping current 6-10In (± 20%), total breaking time ≤ 0.05 seconds.

Optional attachments and extended features

The E series supports multiple accessory extensions, which can be flexibly matched according to control and monitoring needs to enhance the functionality and adaptability of circuit breakers

Shunt Trip: Receive external control signals (such as fire linkage and remote commands) to achieve remote tripping and adapt to scenarios that require centralized control.

Under Voltage: When the circuit voltage is lower than the set value, it automatically trips to protect voltage sensitive equipment (such as precision instruments and motors).

Aux. Contacts: Used to provide feedback on the on/off status of circuit breakers (such as "closed" and "tripped" signals), compatible with automated monitoring systems.

Trip Alarm Contacts: When the circuit breaker trips due to overload or short circuit, an alarm signal is issued to facilitate troubleshooting and maintenance.

Application scenarios and selection suggestions

（1） Core application areas

In the field of industrial production: power distribution protection for factory workshops, industrial plants, and production lines, overload and short circuit protection for equipment such as motors, pumps, and fans. The EK frame 320-630A series is recommended (EHK sub series is preferred, with high breaking capacity more suitable for industrial scenarios).