INTRODUCTION

BE3 ac voltage relays provide voltage monitoring and protection in

both single-phase and three-phase systems. They are used in

applications such as utility mains failure, regulation of power

supplies, and to protect voltage sensitive equipment. Undervoltage,

overvoltage, and combined over/undervoltage units are available.

BE3 ac voltage relays operate when the adjustable trip point is

reached. An external time delay control is provided with an

adjustment of 0 to 10 seconds (relay operating time is typically 200

milliseconds). This time delay may be used to prevent false tripping

when there are slight variations in the voltage supply. 

On overvoltage units, the output relay energizes when the input

signal exceeds the trip point. On undervoltage units, the output

relay de energizes when the input signal goes below the trip point.

A red LED indicates the state of the relay. A green LED indicates

the condition of the power supply.

The BE1-CDS240 Current Differential System is an economical, microprocessor based, multifunction

system that provides a four input, three-phase percentage differential with harmonic restraint protection.

Also included is three-phase with voltage control, ground, and negative-sequence overcurrent protection,

voltage and frequency protection, breaker failure for up to four breakers, breaker monitoring for four

breakers, transformer monitoring, and metering functions, all in an integrated system with several

communications options. The BE1-CDS240 Current Differential System is intended for use in any low

impedance current differential protection application including transformer, generator, motor, and bus

protection. Four setting groups are provided for adaptive relaying with automatic selection logic for cold

load pickup and/or dynamic setting group changes.

The BE1-CDS240 is available in a fully draw-out MX case with configurations for horizontal 19″ rack

mounting, horizontal panel mounting and vertical panel mounting. BE1-CDS240 features include:

• Up to four restraint inputs (four three-phase current circuits) and two virtual current circuits that

can be used with any combination of two current inputs

• Independent ground input

• Three voltage inputs (Va, Vb, Vc, to Vn)

• Three-phase percentage differential protection with harmonic restraint

• Three-phase voltage, frequency and overcurrent protection

• Four setting groups

• One embedded preprogrammed logic scheme

• Fourteen or 10 programmable outputs

• Eight or 12 contact sensing inputs

• Breaker failure protection for four breakers

• Front panel HMI (human-machine interface)

• Communications ports: one front RS-232, one rear RS-232, one rear RS-485 and one rear

IRIG port

• Communications protocols available: DNP3, Modbus® RTU, and ASCII

• Sequence of events recording

• Fault recording

• Oscillography

• Demand reporting

• Differential current monitoring

• Optional load profile reporting

INSTALLATION

BE3 temperature relays are designed for mounting on

standard DIN rails that comply with DIN-EN 50022.

Mounting involves hooking the top edge of the cutout on the

base of the case over one edge of the DIN rail. The opposite

side of the cutout containing the release clip is then pushed

over the opposite side of the DIN rail. To remove or

reposition the relay, lever the release clip and move the

relay as required. BE3 relays should be installed in a dry,

vibration-free location where the ambient temperature does

not exceed the operating temperature range. Connections to

the relay should be made using wire that meets applicable

codes and is properly sized for the application. Figure 2

illustrates the terminal connections for the BE3-49R

temperature relay.

A burden resistor must be installed across all unused RTD

inputs that are not connected to an actual RTD. For units

with style number 5HXXX, it is suggested that a 10 Ω

resistor be connected across any unused RTD inputs. For

units with style number 5IXXX, it is suggested that a 100 Ω

resistor be connected across any unused RTD inputs. The

minimum power rating for the burden resistors is ¼ W.

INTRODUCTION

Three-input BE3 temperature relays use resistance

temperature detectors (RTDs) to monitor remote

temperatures. When any of three monitored temperatures

exceeds a preset limit, the corresponding relay output

operates. A dc metering output indicates the highest

temperature of the three RTDs. BE3 temperature relays are

available for use with 10 Ω copper or 100 Ω platinum RTDs.

OPERATION

Three temperatures are monitored through RTDs connected

at the nine-position front panel connector. RTD connections

are labeled A, B, and C. Three user-adjustable controls are

located on the front panel: SET 1. SET 2. and SET 3. Each

setpoint is adjustable from 50 to 100% (±3%) of the RTD

temperature range. When a setpoint is exceeded, the

corresponding TRIP LED lights and the relay output

energizes. Each RTD has a corresponding LED to identify

which RTD has exceeded the temperature setpoint. For

example, if the temperature of RTDs B and C exceeds the

trip level, the B and C TRIP LEDs light and the relay output

energizes. A green LED labeled AUX indicates the power

supply status. Figure 1 illustrates the BE3-49R controls,

indicators, and terminals.

Synchronous Motor Application (SCP 250-M)

In synchronous motor applications, the SCP 250 allows the desired operating power factor to be pre

programmed so that the motor power factor remains constant during normal loading conditions. During

transient loading conditions, the SCP 250 makes corrective motor field excitation adjustments through a

regulator or exciter-regulator and thereby minimizes the possibility of synchronous pullout.

FEATURES

SCP 250 Var/Power Factor Controllers have the following features.

• Suitable for use in generator or synchronous motor applications

• Provide system control over a wide range of loading conditions

• Accommodate standard voltage sensing inputs

• Front panel selection of either var or power factor control

• Do not require use of motor operated control

• Specifically designed to operate with the standard Basler SR , KR, selected AVCs, SSR regulator

series, and SSE static exciter-regulators

• During power factor control, reactive load changes automatically when kW load is changed

• Easily calibrated on site

• UL recognized and CSA certified

Generator Peaking Application (SCP 250-G)

In peaking generator applications, the paralleling circuit of a voltage regulator presents large changes in

reactive current when the bus voltage changes by a relatively small amount. However, the regulator’s

ability to compensate for large changes in bus voltage can be exceeded. Two examples illustrate typical

problem areas.

Example 1. A generator equipped with a voltage regulator adjusted for 4% droop can

have a variation in var load from zero to 100% with a 4% decrease in bus voltage.

Further decreases in bus voltage would overload the generator.

Example 2. An increase in bus voltage can cause leading power factor conditions with

the associated danger of the machine pulling out of synchronization.

To minimize the possibility of either example occurring, the SCP 250 is used and adjusted for operation in

a “safe” region with either a regulated “fixed” var level or a “fixed” power factor. Thus, for a large change

in reactive current due to bus voltage changes, the operating generator is unaffected.

FEATURES

SCP 250 Var/Power Factor Controllers have the following features.

• Suitable for use in generator or synchronous motor applications

• Provide system control over a wide range of loading conditions

• Accommodate standard voltage sensing inputs

• Front panel selection of either var or power factor control

• Do not require use of motor operated control

• Specifically designed to operate with the standard Basler SR , KR, selected AVCs, SSR regulator

series, and SSE static exciter-regulators

• During power factor control, reactive load changes automatically when kW load is changed

• Easily calibrated on site

• UL recognized and CSA certified

APPLICATION

The SCP 250 is suitable for use in generator peaking and synchronous motor applications.

INTRODUCTION

The SCP 250 controls generator (SCP 250-G) or motor (SCP 250-M) power factor or vars by monitoring

the voltage and current and supplying a control input to a voltage regulator.

When the SCP 250 is controlling vars, the voltage regulator (or static exciter) output changes to attain the

selected reactive load current.

When the SCP 250 is controlling power factor, the voltage regulator adjusts the excitation until the

selected power factor is obtained.

The SCP 250 monitors the open/closed state of the circuit breaker so that the voltage regulator controls

excitation when the breaker is open and the SCP 250 controls excitation when the breaker is closed.

A voltage limiting feature in the SCP 250 prevents the voltage regulator from supplying full or no

excitation if utility power is lost and the peaking generator main breaker remains closed. Voltage limiting is

adjustable between ±10% and ±30%.

Because the SCP 250 is designed for behind-the-panel mounting, provisions are included for locating the

Var/PF switch and potentiometer remotely.