SIEMENS VL Molded Case Circuit Breakers - Trip Units
General Information
The interchangeability of the VL circuit breaker trip units allow for easy conversion from any of 3 types of protection. They are thermal-magnetic, electronic, or electronic with a built-in LCD display. The thermal-magnetic trip unit features an adjustable magnetic trip setting. The electronic trip units are microprocessor based true RMS sensing devices and are available with a variety of adjustable trip settings, configurations, and information menus. With precise control over the circuit breaker functions and access to system status, diagnostics, and information, these trip units allow for unsurpassed flexibility in circuit coordination.
An example of coordination is the out of the box Ground Fault function on the Model 545 trip units. The pick-up and time delay settings are fixed for each frame and do not overlap with the settings on the other frames.
Therefore, when VL breakers are used together in a system the GF protection is automatically coordinated. The user also has the ability to program a custom coordination scheme with the high level of adjustability available on the Model 576 trip units.
VL trip units are available for the following applications:
Line Protection - overload and short-circuit curves are matched to protect cables, wiring and non-motorized loads
Motor Circuit Protection - equipped with adjustable instantaneous short-circuit protection, trip characteristics are designed for optimum protection and isolated in combination starter applications (consisting of a motor circuit protector, contactor, and overload relay)
Non-automatic Circuit Breakers (MCS) - can be used as supply, main or non-automatic switches without overload protection. They are fitted with fixed instantaneous settings.
VL Trip Unit Functions Overview ( Click for larger photo )
VL Thermal Magnetic Trip Unit - Model 525
Main features:
Ideal for line protection
Fixed overload protection
Adjustable short-circuit protection
Thermal Magnetic Trip Units, Model 525, combine the inverse time element design for low level overloads, and instantaneous magnetic action for short circuit protection. The standard unit has preset overload protection and an adjustable instantaneous trip setting, with 6 set points. Thermal-Magnetic trip units are available throughout the VL family, from 15 to 1600A.
VL Electronic Trip Unit - Model 545
Main features:
Flashing green LED indicates proper operation
Yellow LED for overload status
Integrated self-test function
Operates without the need for auxiliary voltage
Plug-in socket for field testing device
Electronic trip units are available through the VL family, from 60A (which can be set as low as 30A) up through 1600A . They are also available in four trip configurations (LI, LIG, LSI, LSIG)
On the Model 545 Electronic Trip Unit a flashing LED confirms that the microprocessor in operating and another indicates an overload condition. For ease-of-use and to insure proper coordination, the set points for the continuous current are shown on the face of these trip units in amps.
VL Electronic Trip Unit with LCD - Model 576
Main features:
Integral LCD dispay
User-friendly, menu-driven setting of protection parameters directly in absolute ampere values
Integrated self-test function
Operates without the need for auxiliary voltage when the breaker is under load
Plug-in socket for field testing device
Thermal memory function, selectable on/off
Fully adjustable LSI and LSIG settings for flexible coordination
Connects to communication modules
Electronic trip units are available through the VL family, from 60A (which can be set as low as 30A) up through 1600A . They are also available in four trip configurations (LI, LIG, LSI, LSIG)
On the Model 576, with LCD display, the current in each phase is continuously shown on the display. Unlike many displays, no secondary or auxiliary voltage is required as long as the breaker is energized and a minimal load current is present. These trip units can also indicate the glast triph status (date, time, amps) when they are connected to a PC via one of our communications modules.
