Beckwith Electric M-4172 Digital Motor Bus Transfer System

• Provides Automatic and Manual transfers of motor bus systems on Low

Voltage Switchgears in power plants and industrial processing plants to

ensure process continuity

• Automatically selects Fast, In-Phase, Residual Voltage, and Fixed

Time motor bus transfers, based on varying system conditions

• Applicable for one way and bi-directional Manual transfers

• Can be expanded to accommodate multiple breaker configurations

• Integrated control, supervisory functions, sequence of events, and

oscillograph recording in one device

• Extensive commissioning tools, including ringdown analysis

Standard Features

Automatic Transfer: The digital Motor Bus Transfer System (MBTS)

provides the following Automatic Transfer logic and features:

• Transfer initiated by protective relay external to the MBTS

• Automatic Transfer after a loss of the motor bus supply voltage

based on the programmable undervoltage element. This provides a

selectable backup feature if a protective relay transfer is not initiated.

• Fast Transfer with adjustable phase angle limit, delta voltage limit

and delta frequency limit

• In-Phase Transfer at the first phase coincidence if Fast Transfer is

not possible.

• Residual Voltage Transfer at an adjustable low residual voltage limit

if Fast Transfer is not possible

• Fixed Time Transfer after an adjustable time delay

• Programmable load shedding prior to initiating In‑Phase Residual

Voltage Transfer and Fixed Time Transfer

• Verify the new source (the source to which the bus is being

transferred) is healthy and within acceptable upper and lower voltage

limits

Manual Transfer: When a Manual Transfer is initiated the digital MBTS

provides the following:

• Sync check functions with adjustable parameters

• Hot Parallel Transfer if enabled (make‑before break)

• Fast Transfer, In‑Phase Transfer and Residual Voltage Transfer (if the

Hot Parallel Transfer is disabled)

• Programmable load shedding prior to initiating Residual Voltage

Transfer

• Verify the new source (the source to which the bus is being

transferred) is healthy and within acceptable upper and lower voltage

limits

Circuit Breaker Control: The digital Motor Bus Transfer System includes

the following Circuit Breaker

Control features:

• Control of two circuit breakers with two individual programmable

breaker closing times

• Three-breaker configuration can be provided by two M‑4172 devices

• Breaker status supervision

• Breaker failure monitoring

Additional Standard Features

• Sequential or Simultaneous Transfer Mode

• Bus Phase Undervoltage (27B)

• Frequency (81) and Rate of Change of Frequency (81R) for load

shedding

• Breaker Failure Source 1 and Source 2

• Bus VT Fuse‑Loss Detection (60FL)

• Auto Trip

• Auto Close

• Four dry output contacts (two trip and two close) for Source 1 and

Source 2. one lockout/ blocking output contact, and 3 programmable

output contacts (2 Form "a" and one Form "c")

• Two Breaker Status 52b (or 52a) inputs for the Source 1 and Source

2 breakers, four programmable digital inputs

• All functions can be enabled or disabled

• Remote/Local control selection

• Device ON/OFF Control Selection

• M‑3931 Human‑Machine Interface (HMI) Module

• M‑3976 Status Module

• IRIG‑B time synchronization

• Oscillographic recording

• Two RS‑232 ports (front and rear) and one RS‑485 port* (rear)

*When using M‑3871 ISScom V10.02.XX to communicate with M‑4172

units with Firmware version V03.00.XX and higher, the RS‑485 port

(COM 3) is not available.

• S‑4200 or M‑3871 ISScom® Communications and Oscillographic

Analysis Software

Optional Features

• 5 A or 1 A models available

• 60 Hz or 50 Hz models available

• Available in vertical panel mount

• Redundant Power Supply

• External TCM and CCM available

• Ethernet port RJ‑45 10/100 Base‑T (MODBUS over TCP/IP)

• Ethernet port RJ‑45 10/100 Base‑T (IEC 61850 Protocol)