Rockwell-automation 810 5.0: Inverse Time Current Relays User Manual download pdf

INSTRUCTIONS

BULLETIN

810

INVERSE TIME CURRENT RELAYS

IMPORTANT - Save for future

reference.

Bulletin 810

rela

with a maximu

continuous

of 60 amperes.

OPERATING

FLUID

PISTON

COIL

CORE

DASHPOT

SILICONE

Cross sectional view.

Moving parts are shaded.

DESCRIPTION

-The Bulletin 810 is a

magnetically operated current relay,

with time delay, for use on AC or DC

applications. It has inverse time-current

characteristics which are dependent.

upon the viscosity of the fluid in the

dashpot. However, unlike thermal re-

lays, minimum operating current is inde-

pendent of ambient temperature change

or cumulative heating. The relays are

supplied as standard with

a normally

closed (NC) contact and an automatic

reset. Available options are a normally

open (NO) contact, hand reset, and

bifurcated contacts with a clear plastic

(poly-carbonate) cover. Tripping current

and time delay are adjustable.

TIME DELAY TRIP - Current relays are

used when it is desirable to take a motor

off the line in a certain period of time after

a predetermined load condition is

reached. A typical application would be

starting a large motor, where the Bulletin

810 is used to automatically open the

motor starter control circuit if the motor is

CONTACT RATINGS -

AC DC

Maximum Contact Rating Per Pole

NEMA Rating Designation A600

Max AC

Voltage

Carrying

Continuous

Volt-amperes

Ampere

Amperes

Range

Rating

60 or 50

Make Break

Current

Make

Break

120

240

7200 720 115-125

7200 720 230-250

00.4

0.2

480 1.5 10

7200 720 550-600 0.1

600 1 12 1 1.2

7200

720

not up to speed in the maximum accel-

eration time allowed. In this and other

applications of the automatic reset type

relay, three wire control must be used,

with a provision for interrupting the cur-

rent through the relay coil immediately

after the relay trips (see typical schema-

tic diagram on page 3). On two wire con-

trol applications such as float switches,

pressure switches or thermostats, a

hand reset type overload relay must be

used to provide this protection to the coil.

The relay can carry its rated continuous

current in the non-tripped position only.

OPERATION -

Current through the Bul-

letin 810 operating coil imparts an elec-

tromagnetic force on the movable core.

The vertical position of the core in the

coil is adjustable, thereby providing an

adjustable trip point. When the coil cur-

rent increases to the trip point, the core

raises to operate the contact mecha-

nism. Time delay is provided by a sili-

cone fluid dashpot mounted below the

core and coil assembly. An adjustable

valve in the dashpot piston provides for

time delay adjustment.

piston reaches an increased diameter in

the dashpot, where it is free, to trip the

contact with a quick action. Time and

current required to complete this cycle

are inversely related as shown by the

time-current characteristics curves on

page 2.

RESET - Standard models of the Bulle-

tin 810 are automatically reset as soon

as the current through the coil is inter-

rupted or decreased to approximately

20% of the tripping current. The core is

designed to drop quickly, returning the

contacts to their normal position. A

check valve allows the piston to bypass

the fluid in its return to the bottom of the

dashpot. The action of hand reset mod-

els differs only in that the contacts do not

reset until a lever on the contact block is

operated. There is no waiting period as

with thermal relays.

NORMAL CURRENT

The electro-

magnetic force caused by normal con-

tinuous current through the operating

coil is not great enough to lift the core

and piston. The relay remains

inoperative.

OVERCURRENT- When the current

through the operating coil increases

beyond the trip point, the resultant elec-

tromagnetic force causes the core and

piston to raise. Upward motion is damp-

ened through the use of the silicone fluid

dashpot The core rises slowly until the

EFFECTS OF AMBIENT TEMPERATURE

The minimum operating current

(100% on the time-current characteris-

tics graph) is independent of ambient

temperature at the relay. However, the

operating time at overcurrent varies

directly to the viscosity of the silicone

fluid. Since the viscosity varies inversely

with ambient temperature, the operating

time is also inversely affected. The time

temperature table shows the correction

factors to be applied to the operating

times for various temperatures.

TIME TEMPERATURE RELATIONSHIP

( +

40°C

Reference)

Ambient

Temperature

(“C)

‘”

+lO"

+20"

+30"

+40"

Operating Time

Correction Factor

2.25 1.80 1.45 1.20 1.0

Publication 810-5.0 - April, 1983

Supersedes Publication 810-5.0, Dated December, 1980

1 2 3 4 5

Summary of Contents

Page 1 - INVERSE TIME CURRENT RELAYS

INSTRUCTIONSIBULLETIN810INVERSE TIME CURRENT RELAYSIIMPORTANT - Save for futurereference.Bulletin 810 relawith a maximucontinuousof 60 amperes.OPERATI

Page 2 - With Series A Fluid

OPERATING CURRENT ADJUSTMENT - stamped on the nameplate. After the(Not necessary if factory set to user’s core and dashpot assembly is

Page 3

ADDING DASHPOT FLUID - (See notePage 2) The dashpot fluid is shippedseparately. To add fluid, remove the coreand dashpot assembly by unfasteningthe sp

Page 4 - I CORE ASSEMBLY

TO REPLACE THE COIL - Remove thedashpot assembly, contact block, in-sulator, and coil terminations. On steelpanel mounted relays also removenameplate

Page 5