Обзор

3VL molded case circuit breakers according to UL 489/IEC 60947-2 up to 1600 A

Область применения

The different versions of SENTRON 3VL UL circuit breakers are suitable for the following applications:

• Incoming (feeder) and outgoing (branch) circuit breakers in distribution systems
• Switching and protection devices for motors (motor protection together with contactor and motor protection relay), transformers and capacitors
• Disconnector units with features for stopping and switching off in an emergency (main control switches and EMERGENCY-STOP switches) in conjunction with lockable rotary operating mechanisms.

The SENTRON 3VL UL circuit breakers are available in the following versions:

1. For system protection (in 3-pole Versions)
The overload and short-circuit releases are designed for the protection of cables, leads and non-motor loads.

2. For starter combinations (in 3-pole version)
These circuit breakers are used both for short-circuit protection as well as for isolating functions, which may be required in starter combinations consisting of circuit breakers, overload relays and motor contactors. These circuit breakers exclusively feature adjustable, instantaneous short-circuit releases.

3. As non-automatic air circuit breakers (in 3-pole Versions)
These circuit breakers can be used as feeder circuit breakers, main control switches or disconnectors without overload protection. They incorporate an integrated short-circuit self-protection system.

Standards and specifications

SENTRON 3VL UL circuit breakers comply with:

UL 489,
CSA (CSA - C22.2),
IEC/EN 60947-2,
isolating features according to IEC 60947-2, EN 60947-2,
NOM (NMX-J-266-ANCE-2002) on request.

Please contact Siemens for details of other standards.

Operating conditions

The SENTRON 3VL UL circuit breakers are designed for operation in enclosed areas.

Особенности

• The compact design of the SENTRON 3VL circuit breakers coupled with excellent characteristics fulfills the high demands of today's electrical distribution systems.
• These circuit breakers offer a broad product range, improved technology, space savings and easy operation.
• They are available both in thermal-magnetic (20 A to 1600 A) and in solid-state versions (30 A to 1600 A).

Дизайн

• Rated current range from 20 A to 1600 A
• Different switching capacity for each size

N	Standard (35 kA)
H	High (65 kA)
L	Very high (100 kA)

• No derating or loss of performance up to 40 °C
• Solid-state overcurrent trip units from size 150 A (VL150 UL, DG-Frame), particularly for time-based discrimination and ground-fault protection
• 2 families of internal accessories
• Full range of external accessories e.g. terminals for aluminum cable.

All circuit breakers are supplied with integrated electronic trip units. The SENTRON VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers are available with different connection versions (see "Connections, Basic Equipment and Options"). Auxiliary switches/alarm switches or auxiliary trip units can be easily adapted by the customer, or they are also available ready installed if required.

The switching capacity is shown on the front of every circuit breaker.

• Standard switching capacity:
  I_cu = 35 kA at AC 50/60 Hz 480 V
• High switching capacity:
  I_cu = 65 kA at AC 50/60 Hz 480 V
• Very high switching capacity:
  I_cu = 100 kA at AC 50/60 Hz 480 V

Standards and specifications

SENTRON 3VL UL circuit breakers comply with:

UL 489,
CSA (CSA - C22.2),
IEC/EN 60947-2,
Isolating features according to IEC 60947-2, EN 60947-2,
NOM (NMX-J-266-ANCE-2002) upon request.

Please contact Siemens for details of other standards.

The SENTRON 3VL UL circuit breakers comply in addition with requirements for "disconnector units with features for stopping and switching off in an emergency" (EMERGENCY-STOP switches) in conjunction with lockable rotary operating mechanisms (red-yellow) and terminal covers.

Please contact Siemens for details of other standards.

Connection

The following connection types are available for the SENTRON 3VL and approved according to UL 489:

• Box terminal, suitable for stranded conductors
• Screw connection for flat connector
• Circular conductor/multiple feed terminal (for Al-/Cu cable)
• Cable lug connection

The incoming and outgoing terminals for the circuit breaker can be freely selected. The electrical specifications remain the same.

Bare conductors at the top connections must be insulated in the arc quenching space that is necessary above the arc chutes.

For the SENTRON VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers, the connections for the internal accessories (auxiliary trip units, auxiliary switches and alarm switches) are supplied with terminal screws.

The auxiliary trip units (shunt trip units and undervoltage trip units), auxiliary switches and alarm switches for all SENTRON 3VL circuit breakers can be connected easily and directly.

The motorized operating mechanisms with stored-energy features are always equipped with terminals. The leading auxiliary switches for the rotary operating mechanisms are always supplied with connecting cables.

SENTRON VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers

The main components of the SENTRON 3VL UL circuit breakers are the three conducting paths with the incoming and outgoing terminals. The fixed and moving contacts are designed in such a way that the contacts are magnetically repelled if there is a short-circuit. In conjunction with the arcing chambers, a dynamic impedance is created that causes current limiting due to a reduction in the damaging effects of I²t and I_p-energy that arises during short-circuits.

The circuit breaker is trip-free.

To the right and left of the operating mechanism, the double-insulated accessory compartments are situated for the auxiliary trip units and auxiliary switches.

The trip units for the SENTRON VL150X UL (CG frame) to VL1600 UL (PG frame) have the following features:

• The trip units are available in thermal-magnetic and electronic versions (VL150X UL (CG frame) only in thermal-magnetic version).
• The thermal-magnetic trip units have permanently set overload releases and adjustable short-circuit releases (VL150X UL (CG frame) only with permanently set short-circuit release).

As is the case for all versions of the SENTRON 3VL UL circuit breakers with electronic trip units, the current transformers are in the same enclosure as the trip units. They send a signal which is proportional to the load current to the electronic overcurrent tripping unit.

All SENTRON 3VL UL circuit breakers with electronic trip units measure the actual r.m.s. current. This type of measurement is the most accurate method. Currents in today's electrical distribution systems with many harmonics are evaluated reliably.

Overcurrent trip unit systems

The trip unit is delivered ex-works with the switch unit. The infeed and outgoing terminals for the circuit breaker can only be freely selected for complete switches.

1. Overcurrent trip units for the SENTRON VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers, thermal-magnetic

The overcurrent and short-circuit releases work with bimetallic and magnetic trip units. They are available with fixed set overcurrent trip units and settable short-circuit trips units.

The circuit breakers for starter combination applications are usually combined with a motor contactor and a suitable overload relay.

The non-automatic air circuit breakers have an integrated short-circuit self-protection system eliminating the need for back-up fuses. Non-automatic air circuit breakers have no overload protection.

2. Overcurrent trips of the SENTRON circuit breaker VL150 UL (DG -Frame) to VL1600 UL (PG-Frame) are electronic, ETU

The electronic overcurrent trip unit system consists of:

• 3 current transformers
• Evaluation electronics with microprocessor
• Internal power supply, no external auxiliary voltage necessary
• Tripping solenoid

The left accessory compartment is required for the trip magnets for the SENTRON VL150 UL (DG frame) and VL250 (FG frame).

The protection functions of the solid-state overcurrent trip units are maintained without additional auxiliary voltage. The electronic trip units are supplied with energy through circuit breaker-internal current transformers.

The solid-state overcurrent trip unit has to be activated for parameterizing. This requires a load current of at least 20 % of the respective rated current I_n of the circuit breaker. If this load current is not available, the necessary auxiliary power can be fed in through a 3VL9 000-8AP01 battery power supply or through the 3VL9 000-8AK01 function tester. For communication-capable circuit breakers the trip unit is supplied with energy through COM10.

At the output of the electronic overcurrent trip unit module there is a tripping solenoid which trips in the case of overload or short-circuit.

Abbreviations (functions)
L	= Long Time Delay
S	= Short Time Delay
I	= Short-Circuit Protection (Instantaneous)
N	= Neutral Protection
G	= Ground Fault Protection

SENTRON VL150 UL (DG -Frame) to VL1600 UL (PG-Frame) electronic trip units – Overview of functions

Internal accessories (auxiliary switches, undervoltage trip units, shunt trip units)

The SENTRON 3VL UL circuit breakers can be supplied with all the internal accessories (e.g. auxiliary switches, undervoltage trip units or shunt trip units). The available versions can be found in the tables with the Order No. supplements.

Fixed-mounted, plug-in or withdrawable version

The fixed-mounted circuit breaker is the basic version. This can be converted very easily into a plug-in or withdrawable version with the aid of the appropriate installation kit. This kit contains blade contacts, a locking pin and terminal covers for the plug-in version. The assembly kit for the withdrawable version also contains side covers and a moving mechanism. Even with the masking frame mounted, it is still possible to move using the handle with the door closed.

Operating mechanisms

The basic versions of the SENTRON 3VL UL circuit breakers are equipped with a toggle lever as an operating mechanism which is also used as a switch position indicator. In addition to "ON" and "OFF", "Tripped" is also indicated.

The toggle lever assumes the "tripped" position when the internal tripping mechanism is activated by an overcurrent tripping, e.g. an overload or short-circuit. The activation of an undervoltage trip unit or shunt trip unit also causes the toggle lever to assume the "tripped" position. The toggle lever must be put into the "OFF/RESET" position before the circuit breakers can be reclosed. It will then be possible to reset the internal tripping mechanism and reclose the main contacts on the circuit breaker (see figure).

A toggle lever extension is supplied with the SENTRON VL 1200 UL (NG-Frame) and VL1600 UL (PG-Frame) circuit breakers. This accessory must be ordered separately for SENTRON VL400 UL (JG-Frame) to VL800 UL (MG-Frame), if required.

Front-operated rotary operating mechanisms

These operating mechanisms have been designed for direct mounting to the circuit breaker and change the toggle lever movement from a linear to a rotary motion.

A leading voltage can be applied to the undervoltage trip unit of a circuit breaker with leading auxiliary switches which makes the circuit breaker ready-to-close.

Door-coupling rotary operating mechanisms (complete operating mechanisms)

Door-coupling rotary operating mechanisms and removable covers are available for circuit breakers which are installed into control cabinets and distribution boards. These are supplied as complete sets, including an articulated-shaft mechanism.

With regard to the switching status indication and the "RESET" position, the same applies to the rotary operating mechanisms as to the toggle lever. The position of the operator lever (knob) indicates the status.

This means that all SENTRON 3VL UL circuit breakers which have these rotary operating mechanisms as well as the corresponding terminal covers can be used as main control switches.

Toggle lever operating mechanism positions

Rotary operating mechanism secured with a padlock

Motorized operating mechanisms

The SENTRON VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers can be equipped with motorized operating mechanism for remote opening and closing during operation.

These motorized operating mechanisms for SENTRON VL150X UL (CG frame) to VL800 UL (MG frame) circuit breakers have a spring energy store (for synchronization) with a maximum ON period of t_E ≤ 100 ms.

For SENTRON VL1200 UL (NG-Frame) and VL1600 UL (PG-Frame) circuit breakers there are motorized operating mechanisms without a spring energy store for remote-controlled ON and OFF switching.

All motorized operating mechanisms are always supplied with a locking device for padlocks. Optional safety locks are also available for motorized operating mechanisms with spring energy store.

These locking devices can be used to block the operating mechanism electrically and mechanically. All remote-controlled operating mechanisms are equipped with a manual operation option for maintenance purposes.

The motorized operating mechanisms with spring energy store for VL150X UL (CG frame) to VL800 UL (MG frame) as well as the motorized operating mechanisms for VL1200 UL (NG frame) and VL1600 UL (PG frame) are each equipped inside with a signaling contact (NO) for the following functions:

Main circuit connections, basic equipment and options

Box terminal (for copper cable)	Connection with screw connection (metric/inch)	Circular conductor/Multiple feed terminal (for Al-/Cu cable)

Main circuit connections (for conductor cross-sections see "Technical Specifications" )
Motor starter protectors/circuit breakers	Connection overview and further options
	Box terminals	Screw terminals for flat connector	Screw terminals for flat connector	Circular conductor terminals/multiple feed-in terminals	Rear-mounting terminals	Cable lug connection	Direct connection of busbars is possible (for IEC-approved circuit breakers only)
	Only Cu	With metric thread	With inch thread	Cu or Al
VL150X UL (CG frame)	x	x	--	x	x	--	x
VL150 UL (DG-Frame)		x	x	x	x	--	x
VL250 UL (FG-Frame)	x	x	x	x	x	x	x
VL400 UL (JG-Frame)	x	x	--	X1)2)	x	x	x
VL400X UL (LG-Frame)	--	x	x	x1)2)	x	x	x
VL800 UL (MG-Frame)	--	x	x	x1)	x	x	x
VL1200 UL (NG-Frame)	--	x	x	x1)	x	x	x
VL1600 UL (PG-Frame)	--	x	x	x1)	x	--	x

X Available

-- Not available

1) Multiple feed terminal.

2) Circular conductor terminal also available.

Auxiliary switches and auxiliary trip units

Undervoltage trip units, leading auxiliary switches

If there is no voltage present, closing of the circuit breaker is not possible. If voltage is not applied to the trip units, operation of the circuit breaker will result in no-load switching.

Frequent re-tripping should be avoided because of its adverse effect on the endurance of the circuit breaker.

A leading voltage can be applied to the undervoltage trip unit of a circuit breaker with leading auxiliary switches which makes the circuit breaker ready-to-close.

For SENTRON 3VL UL circuit breakers, the leading auxiliary switch can be supplied with the front rotary operating mechanism or complete operating mechanism. For more detailed information please refer to the selection and ordering tables for accessories.

Shunt trip units

The shunt trip unit is used for remote tripping of the circuit breaker.

The coil of the shunt trip unit is designed for short-time operation only. A coil trip is implemented internally.

It is not permissible to apply a continuous trip command to a shunt trip unit to prevent closing when the circuit breaker is tripped. A central tap is provided as standard for checking the conductivity of the coil.

Possible complement for the insulated accessory subsections in the SENTRON 3VL UL circuit breakers

Before ordering, use the table above to check whether the required combination of shunt trip units, undervoltage trip units and auxiliary/alarm switches is feasible.

Auxiliary switches

Auxiliary switches (HS) are used for indication and control. The contacts of the auxiliary switches close and open together with the main contacts.

Alarm switches

The alarm switches (AS) are active when the circuit breaker has been tripped due to an overcurrent e.g. overload or short-circuit. However, they are also activated if the circuit breaker has been tripped by a shunt trip unit or undervoltage trip unit.

Installation of internal accessories

The insulated accessory subsections for installing accessories (auxiliary trip units and auxiliary switches/alarm switches) have the designations X1, X2 and X4.

The equipping of the circuit breaker with internal accessories and the configuration possibilities for circuit breakers with auxiliary trip units and auxiliary switches/alarm switches depend on the mounting position and size of the circuit breaker (see the illustration "Possible Complements for the Insulated Accessory Subsections of the 3VL UL Circuit Breakers").

PLC control

The auxiliary and alarm switches can be used to send signals to PLCs. These switch blocks are part of the Siemens 3SB3 range.

Leading auxiliary switches

The leading auxiliary switches OFF to ON or ON to OFF are available as a retrofit set for rotary operating mechanisms.

Функции

Current limiting1)

The SENTRON 3VL UL circuit breakers utilize the design principle of magnetic repulsion of the contacts. The contacts open before the anticipated peak value of the short-circuit current is achieved. The current-limiting effects of the SENTRON 3VL UL circuit breakers provide effective protection for system components against the thermal and dynamic effects of the short-circuit current in the event of an electrical fault.

1) Current limiting according to IEC 60947-2.

Ground-fault protection

Ground-fault release "G" sense fault currents that flow to round and that can cause fire in the plant. Several circuit breakers connected in series can provide graduated discrimination by means of the adjustable delay time.

The following measurement methods can be used to detect neutral conductor and ground-fault currents:

Vectorial summation current formation (measurement method 1)

Ground-fault detection in symmetrically loaded systems

The three phase currents are evaluated with the help of the vectorial summation current formation.

Ground-fault detection in asymmetrically loaded systems

The neutral conductor current is measured directly. For the 3-pole circuit breakers, this measurement is only evaluated for ground-fault protection. The electronic trip unit determines the ground-fault current for the three phase currents and neutral conductor current by means of vectorial summation current formation.

3-pole circuit breaker, current transformer in the neutral conductor

Direct detection of the ground-fault current through a current transformer in the grounded neutral point of the transformer (measurement method 2)

The current transformer is installed directly in the grounded neutral point of the transformer.

3-pole circuit breakers, current transformers in the grounded neutral point of the transformer.

Transformer protection

The SENTRON 3VL UL circuit-breakers protect energy distribution systems against overload and short-circuit on the low-voltage side of the infeed transformer. The resulting requirements with respect to current-based and/or time-based discrimination are reliably fulfilled by the SENTRON 3VL UL circuit-breakers for system protection (equipped with thermal-magnetic (TM) or electronic overcurrent trip units (ETU or LCD ETU).

Thermal-magnetic overcurrent trip unit

	Application: System protection – TM, LI/LIN function Overload protection, fixed, short-circuit protection, fixed; VL150X (CG frame), trip units installed in the switch enclosure; Version KM
	Application: System protection – TM/model 525, LI/LIN function Overload protection, fixed, short-circuit protection, adjustable Ii = 5 to 10 × In, for VL150 UL (DG frame) to VL1600 UL (PG frame); Version KN
	Application: Starter protection – M, I function Short-circuit protection, adjustable Ii = 3 to 16 × In1, for VL150 UL (DG frame) to VL1200 UL (NG frame); Version KJ, KK, KL

1) Size dependent, see "Selection and Ordering Data".

Electronic trip units ETU

For types VL150 UL (DG frame) to VL1600 UL (PG frame)	General information: No auxiliary voltage for tripping unit required All ETUs have a thermal image memory Flashing green LED indicates faultless operation of microprocessor	Overload status (I > 1.05 × IR) is indicated by a continuous yellow LED (Alarm) Integrated self-test function Female connector for test unit
	Application: System protection – model 545, LI/LIN function (corresponds to ETU10) Overload protection IR = 0.4 to 1 × In, time-lag class tR = 2.5 to 30 Short-circuit protection (instantaneous) Ii = 1.25 to 11 × In1); Version GB
	Application: System and generator protection – model 545, LSI/LSIN function (corresponds to ETU20) Overload protection IR = 0.4 to 1 × In, Short-circuit protection (short-time delayed) Isd = 1.5 to 10 × IR1), tsd = 0 to 0.5 s, I 2 t selectable on/off Short-circuit protection (instantaneous) Ii = 11 × In (fixed)1) Version GE
	Application: System protection – model 545, LIG/LING function (corresponds to ETU12) Overload protection IR = 0.4 to 1 × In, time-lag class tR = 2.5 to 30 Short-circuit protection (instantaneous) I = 1.25 to 11 × In1) Ground-fault protection: Measurement method 1: (GR) vectorial summation current formation for the currents of the three phases/and neutral conductor (four-conductor systems); IΔn = In Version GD
	Application: System and generator protection – model 545, LSIG/LSING function (corresponds to ETU22) Overload protection IR = 0.4 to 1 × In, Short-circuit protection (short-time delayed) Isd = 1.5 to 10 × IR, tsd = 0 to 0.5 s, I 2 t selectable on/off Short-circuit protection (instantaneous) Ii = 11 × In (fixed)1) Ground-fault protection: Measurement method 1: (GR) vectorial summation current formation for the currents of the three phases/and neutral conductor (four-conductor systems); IΔn = In Version GH

1) Size dependent, see "Selection and Ordering Data".

Solid-state overcurrent trip unit LCD ETU

	General information: No auxiliary voltage for tripping unit required Current indicator Illuminated LCD display indicates faultless operation of microprocessor The overload status (I > 105 % IR) is indicated by "overload" on the LCD display	User-friendly, menu-driven setting of protection parameters in absolute ampere values by means of keys Integrated self-test function Female connector for test unit Communication link to PROFIBUS DP is possible.
	Application: System protection – model 576, LSI/LSIN functions (corresponds to ETU40) Overload protection IR = 0.4 to 1 × In, time-lag class tR = 2.5 to 30 On/off selectable thermal image Short-circuit protection (short-time delayed) Isd = 1.25 to 10 × IR1), tsd = 0 to 0.5 s, I 2 t selectable on/off Short-circuit protection (instantaneous) Ii = 1.25 to 11 × In1) Version JH
	Application: System protection – model 576, LSIG/LSING function (corresponds to ETU42) Overload protection IR = 0.4 to 1 x In, time-lag class tR = 2.5 to 30 On/off selectable thermal image Short-circuit protection (short-time delayed) Isd = 1.25 to 10 × IR1), tsd = 0 to 0.5 s, I 2 t selectable on/off Short-circuit protection (instantaneous) Ii = 1.25 to 11 × In1) Ground-fault protection: Measurement method 1: (GR) vectorial summation current formation for the currents of the three phases/and neutral conductor (four-conductor systems); IΔn = 0.4 to 1 × In. Measurement method 2: (GGND) direct detection of ground-fault current by means of current transformer, Ig = 0.4 to 1 × In, tg = 0.1 to 0.5 s Version JM

1) Size dependent, see "Selection and Ordering Data".

Конфигурация

Communication

Two alternatives are available for communication. An LCD ETU (model 576) is required in addition for the more extensive communication with COM10. It is possible to switch on and off using an optional motorized operating mechanism.

Transmittable data

	Data transmission using COM10
Commands: Switch ON/OFF Delete alarm and tripping memory, min/max measured values and maintenance information	✓ ✓
Operating states: ON or OFF status trip position	✓
Event signals Tripped signal with trip current and time stamp Warning messages with time stamp (e.g. overload, phase­asymmetric current etc.) Exceeded threshold value with time stamp (e.g. phase currents)	✓ ✓ ✓
Measured values: Phase currents and neutral conductor current, each with min/max value and time stamp	✓
Parameter values Read and write	✓
Maintenance information: (e.g. number of tripping operations, number of switching operations)	✓
Device identification data	✓
Time synchronization	✓

✓ Available

-- Not available

Functions of the communication components

	Overcurrent trip unit version			COM10 module	Breaker data adapter	Breaker data adapter Plus
	TM	ETU	LCD ETU
Transmission of the operating state (ON, OFF, tripped, warnings, causes of tripping, event log) to the PROFIBUS	--	--	✓	✓	❑	❑
Display of measured values (current only) and parameters in trip unit, change parameters through display	--	--	✓	❑	❑	❑
Transmission of the maximum value of the present current in %	✓	✓	✓	--	❑	❑
Transmission of individual present phase currents incl. min./max. and time stamp	--	--	✓	✓	❑	❑
Transmission of identification data	--	--	✓	✓	❑	❑
Transmission of switch information on HTML basis locally to a PC	--	--	✓	❑	✓	✓
Transmission of switch information on HTML basis through Ethernet	--	--	✓	❑	--	✓
Read out and adjust protection parameters through PROFIBUS	--	--	✓	✓	❑	❑

✓ Required

❑ Not necessary for this function, optionally combinable

-- Function not available

Switching of DC currents

The VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers (for system protection with TM, for starter combinations, non-automatic air circuit breakers) can also be used for DC switching and protection applications.

The VL150X UL (CG frame) to VL1600 UL (PG frame) circuit breakers with electronic trip units (ETU) are not suitable for DC applications.

However, the maximum permitted DC voltage for each conducting path needs to be taken into account for DC switching applications.

Voltages above 250 V at VL150 UL (DG frame) to VL1600 UL (PG frame) require a series connection with 2 or 3 conducting paths.

As the current has to flow through all of the conducting paths, the following connections are recommended in order to satisfy the thermal tripping characteristics.

With DC applications, the response values of the instantaneous short-circuit releases ("I" releases ) are increased by 30 to 40 %.

For 3-pole circuit breakers

Recommended connection/maximum permitted DC voltage Ue		Notes
Circuit A	Circuit B
250 V DC	500 V DC	2-pole switching (non-grounded system)
		If there is no possibility of a ground fault, or if every ground fault is rectified immediately (ground-fault monitoring), then the maximum permitted DC voltage is 500 V (circuit B). With a ground fault, there must always be 2 conducting paths in series for circuit A/3 conducting paths in series for circuit B.

Технические данные

Характеристика

Characteristic curves and certificates

General:

The indicated tripping values for the inverse-time delayed electronic trip units (thermal overload trip releases, "L" trip units) are mean values taken from the spread of all setting ranges from the cold state and under even load conditions on the conducting paths.

The tripping characteristic curves of the instantaneous (electromagnetic) short-circuit releases ("I" trip units) are based on the phase rated current I_n.

For thermomagnetic trip units (TM), the following applies:

The characteristic curves apply to the cold state; at operating temperature, the tripping times of the thermal trip units are reduced to approximately 25 %.

Under normal operating conditions, all three poles of the device must be loaded. The three main current paths must be connected in series in order to protect single-phase or DC loads.

Tripping characteristic curves of the SENTRON VL150 UL (DG frame) to VL1600 UL (PG frame) circuit breakers for generator protection with solid-state overcurrent trip units.

The tripping times of the inverse-time delayed overcurrent trip units apply to the non-preloaded (cold) state. In the operating/warm state (after application of a load at the rated current), the tripping times are reduced to approx. 33 %. After a tripping operation due to overcurrent, the tripping times are reduced in accordance with the dynamic tripping response, which means that a cooling time of a few minutes is required before the next motor start.

Detailed time/current characteristic curves, current limiting characteristic curves, I²t curves and certificates can be ordered from "Technical Assistance" (e-mail: technical-assistance@siemens.com) or downloaded from the following Internet sites:

or