Universal Remote Control MX-880Z - SPECS SHEET Informacje Techniczne Pobierz pdf (Strona 20)

™

Masterpact™ NT and NW Universal Power Circuit Breakers

Micrologic™ Electronic Trip Systems

05/2014

Overview of Micrologic Trip Systems

All Masterpact™ circuit breakers are equipped with the Micrologic trip system to protect power circuits

and loads. Micrologic trip systems use a set of current transformers (called CTs or sensors) to sense

current, a trip unit to evaluate the current, and a tripping solenoid to trip the circuit breaker. Adjustable

rotary switches on the trip unit allow the user to set the proper overcurrent or equipment ground-fault

current protection required in the electrical system. If current exceeds a set value for longer than its set

time delay, the trip system opens the circuit breaker. Alarms may be programmed for remote

indications. Measurements of current, voltage, frequency, power, and power quality optimize continuity

of service and energy management. Micrologic trip units can be changed on-site.

Integration of protection functions in the Application Specific Integrated Circuit (ASIC) electronic

component used in all Micrologic trip units guarantees a high degree of reliability and immunity to

conducted or radiated disturbances. On Micrologic P and H trip units, advanced functions are

managed by an independent microprocessor.

Masterpact circuit breakers are shipped with the long-time pickup switch set at 1.0 and all other trip unit

adjustments set at their lowest settings. Actual settings required for a specific application must be

determined by a qualified consultant or plant engineer. A coordination study is recommended to

provide coordination between all circuit breakers in the distribution system.

Thermal Imaging

The thermal imaging function protects the cables or bus bars from overheating in case of low

amplitude repetitive faults. Such overheating can be due to repetitive motor starting, fluctuating load,

intermittent ground faults, or subsequent closing after a fault.

Traditional electronic protection does not protect against repetitive faults because the duration of each

overload above the pickup setting is too short to achieve effective tripping. Nevertheless, each

overload involves a temperature rise in the installation, the cumulative effect of which could lead to

overheating of the system.

The thermal imaging function remembers and integrates the thermal heating caused by each pickup

setting overrun. Before tripping, the integrated heating value will reduce the associated time delay and,

therefore, the reaction of the trip unit will be closer to the real heating of the power network system.

After tripping, the function will also reduce the time delay when closing the circuit breaker on an

overload.

Model

LS0 LI LSI LSIG

Long-Time +

Short-Time +

Zero Delay

Long-Time +

Instantaneous

Protection

Long-Time + Short-Time

+ Instantaneous

Protection

Long-Time + Short-Time

+ Instantaneous

Protection + Equipment

Ground-Fault Protection

(IEC Rated)

(UL Listed and

ANSI Certified)

(UL LIsted, ANSI

Certified, IEC Rated)

(UL LIsted, ANSI

Certified, IEC Rated)

Basic Trip Unit

A Trip Unit

P Trip Unit

H Trip Unit

2.0

2.0A

—

3.0

3.0A

—

5.0

5.0A

5.0P

5.0H

—

6.0A

6.0P

6.0H

Figure 6: P Trip Unit with Power Metering

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 179 180

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