ABB BL-1 Manuel de démarrage rapide

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Effective February 1978

Supersedes I.L. 41-553.1 F dated January 1976

* Denotes change since previous issue

CAUTION: Before putting relays into service,

remove all blocking which may have been inserted

for the purpose of securing the parts during ship-

ment, make sure that all moving parts operate

freely, inspect the contacts to see that they are

clean and close properly, and operate the relay to

check the settings and electrical connections.

APPLICATION

The type BL-I relay is used primarily for

thermal overload and instantaneous overcurrent

protection of motors and generators, but it may

also be used for the protection of transformers or

any other apparatus if the temperature-rise under

overload is similar to that of motors. The thermal

element is the "replica type" and has a time-

current characteristic closely approximating the

average moderate overload heating curves of

motors. Its characteristics prevent the protected

equipment from being subjected to overloads of

such magnitude or duration as to cause them to

reach dangerous temperatures, but at the same

time permit the utilization of the inherent thermal

capacity of the apparatus.

As its operation depends upon the rate of heat

generation in a heater element within the relay, it

may be used for either ac or dc application. It is

ordinarily connected in the secondary circuit of a

suitable current transformer in ac applications.

Since the voltage drop across the relay must be

within a range of about 0.49 to 0.88 volts at full

load on the protected machine, customary shunts

rated in millivolts are unsuited for dc applications.

However, the drop across a portion of the

protected circuit, such as the interpole field win-

All possible contingencies which may arise during installation, operation, or maintenance, and all details

and variations of this equipment do not purport to be covered by these instructions. If further information

is desired by purchaser regarding this particular installation, operation or maintenance of this equipment,

the local Asea Brown Boveri representative should be contacted.

Courtesy of NationalSwitchgear.com

Company Inc.

ABB Power T&D

Relay Division

Coral Springs, FL 33065

ding of a machine, sometimes can be utilized as a

source of energy for the relay.

CONSTRUCTION AND OPERATION

The single element type BL-1 relay consists of

a heater unit, an instantaneous overcurrent unit,

0 two operation indicators, and a contactor switch.

(Figures

The double element type BL-1 relay contains

two heater units, two instantaneous units, three

0 operation indicators, and a contactor switch.

(Figures 2 & 4).

THERMAL UNIT

The thermal unit consists of a housing of mold-

ed material which encloses a coiled thermostatic

metal spring mounted on a shaft, two die-cut

heater elements made of resistance material, metal

heat storage blocks, and bearings for the shaft;

and, external to the molded housing, a second ther-

mostatic metal spring fastened to the shaft exten-

sion and carrying the moving contact at its outer

end, the stationary contacts, and scales for setting

the stationary contacts at suitable positions for ob-

taining various time-overload operating curves un-

der specified operating conditions.

The external and internal thermostatic metal

springs have identical temperature-angular rota-

tion characteristics, and the external spring is

mounted so that its rotation is in the opposite

direction to that of the internal spring. Conse-

quently, a change in ambient temperature will not

produce an appreciable permanent change in the

position of the moving contacts, although the

Instruction Leaflet

I.L.

Type BL-1 Thermal

Overload Relay

3).

1 &

41-553.1G