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11

Instruction Leaflet 

IL29C614F

Effective December 2011

Instructions for The Digitrip RMS 310 3-Pole and 

4-Pole Trip Unit Installation and Operation with 

K-Frame Series C Circuit Breakers

EATON CORPORATION

 www.eaton.com

4.0  PRINCIPLE OF OPERATION

In open air at 40°C (104°F), an K Frame circuit breaker

with a Digitrip RMS 310 Trip Unit installed will carry cont-

inuously up to 400 amperes without exceeding a 50°C

(122°F) rise at the terminals. The calibration of the trip unit

is insensitive to ambient temperatures over a range of -20

to +55°C (-4 to 131°F)  . However, the trip unit contains

thermal temperature protective circuitry that initiates a trip

operation for self-protection if the internal ambient temp-

erature at the printed circuit board (PCB) reaches approx-

imately 90°C (194°F). This may occur for open air temper-

atures above 40°C with circuit breaker currents near full  

For ambient conditions above 40°C and where the maxi-

mum ampere rating plug has been installed, derating of

the circuit breaker frame should be considered to avoid

exceeding a safe terminal temperature operating range.

Consult Eaton for recommendations. 

4.1  GENERAL

The Digitrip RMS 310 Trip Unit provides a tripping signal

to the flux transfer shunt trip when current and time

delay settings are exceeded. This is accomplished by

employing the Eaton custom designed integrated cir-

circuit Sµre™ chip, which includes a microcomputer

to perform its numeric and logic functions. 

In the Digitrip RMS 310 Trip Unit, all required sensing

and tripping power to operate its 

protection function

is

derived from the current sensors in the circuit breaker.

The secondary currents from these sensors provide the

correct input information for the protection functions, as

well as tripping power, when ever the circuit breaker is

carrying current. These current signals develop voltages

across the appropriate calibrating resistors.

The microcomputer, in cyclic fashion, repeatedly scans

the voltage values across each calibrating resistor and

enters these values into memory. These data are used

to calculate true RMS current values, which are then

repeatedly compared with the protection function settings

and other operating data stored in the memory. The soft-

ware program then determines whether to initiate protec-

tion functions, including tripping the breaker through the

flux transfer shunt trip device in the circuit breaker. 

A green status light indicates the operational status of

the trip unit.  If the load current through the circuit break-

er exceeds approximately 20% of the maximum current

rating of the trip unit, the status light will blink on and off

once each second.  A blinking status light is an indication

of a properly functioning trip unit.  If the status light is not

blinking, the current through the breaker may be less

than 20% of the maximum current rating of the trip unit.

If the current exceeds 20% and the status light is not

blinking, use the STK2 test kit to investigate (see section

6.1).  IF THE STATUS LIGHT IS ON STEADY, IT INDI-

CATES A TRIP IS PENDING.

LACK OF ILLUMINATION OF THE STATUS LED

DOES NOT INDICATE THE TERMINALS OF THE

BREAKER ARE DEENERGIZED.

4.2  OVERLOAD TRIP

In accordance with standards requirements, the trip unit

initiates a trip of the circuit breaker within two hours for

an overload of 135 %, and will trip in less time for higher

overload currents. 

A “Thermal Memory” effect prevents the breaker from

being re-energized immediately after an overload trip. A

“cooling off” period of up to 5 minutes is required, which

allows time for cabling to cool off. 

4.3  SHORT DELAY/INSTANTANEOUS TRIP

For short circuit conditions that exceed the short delay

pick-up settings, the trip unit initiates a trip after a delay

prescribed by the I

2

t ramp function for trip units with cat-

alog number suffixes LS, LSE, LSP, and LSG. A flat

response time delay action is provided by trip units with

catalog number suffixes LSI, LSIE, and LSIG unless the

instantaneous (I) setting is selected. 

4.4  GROUND FAULT PROTECTION

When selected, ground fault pick up and time delay set-

tings shown in Table 

1-2

allow selective ground fault

coordination with other circuit protection devices.

5.0  PROTECTION SETTINGS

5.1  GENERAL

Prior to placing any circuit breaker in operation, each

trip unit protection setting must be set to the values

specified by the engineer responsible for the installation.

The available settings along with the effect of changing

the settings are illustrated in Figures 

12-1

to

12-3

.

The installed rating plug establishes the maximum con-

tinuous current rating (I

n

) of the circuit breaker. Short

delay current settings are defined in multiples of I

n

.

!

CAUTION

load.

Summary of Contents for Digitrip RMS 310

Page 1: ...of Operation 11 5 0 Protection Settings 11 6 0 Testing 12 7 0 Rating Plug 15 8 0 References 15 Effective December 2011 Supersedes IL29C614E 02 09 Instruction Leaflet IL29C614F Instructions for The Di...

Page 2: ...odes and procedures The recommendations and information contained herein are based on Eaton experience and judgment but should not be considered to be all inclusive or covering every application or ci...

Page 3: ...Short Delay Time Ground Fault Pick up KESxxxxLSlG Ground Fault Time 2 0 UL LISTED DEVICES The Digitrip RMS 310 Trip Unit is listed in accordance with Underwriters Laboratories Inc Standard UL489 unde...

Page 4: ...p unit conductor holes at this time If preferred a magnetic screwdriver may be used to position the screws when the trip unit is in the base Make sure shunt plates are centered over shunt plate insert...

Page 5: ...FT 8 TO 10 N M EXCESSIVE TORQUING WILL SHEAR SCREWS FAILURE TO APPLY THE REQUIRED TORQUE MAY LEAD TO EXCESSIVE HEATING AND CAUSE NUI SANCE TRIPPING OF THE CIRCUIT BREAKER Screw in and tighten three tr...

Page 6: ...rce ground or zero sequence ground fault sensing methods If the system neutral is grounded but no phase to neutral loads are used the neutral current sensor is not necessary In that case the white and...

Page 7: ...E NUI SANCE TRIPPING OF THE CIRCUIT BREAKER Screw in and tighten three trip unit retaining screws center first Torque to 6 to 8 lb ft 8 to 10 Nm see Figure 6 To install the ground fault alarm and neut...

Page 8: ...o the trip unit for the alarm leads yellow and green If only one or two sets of leads are required they can be routed to the side or rear as above or one set can be fed to the opposite side through th...

Page 9: ...to position depress the Push to Trip button with a small screwdriver and turn it clockwise one quar ter of a turn until the arrow points to ENGAGED If an adjustable rating plug is used four continuous...

Page 10: ...elay Trip Current and Short Delay Trip Time Adjustment and Curve Details Current In Short Delay Pick up Multiples of Rated Current Time 5 6 4 3 2 2 8 7 8 300 200 100 I I 100 200 300 Figure 12 3 Ground...

Page 11: ...re program then determines whether to initiate protec tion functions including tripping the breaker through the flux transfer shunt trip device in the circuit breaker A green status light indicates th...

Page 12: ...e 1 2 These ampere values are always the same no matter what rating plug is installed in the circuit breaker Available on Catalog Nos KES3xxxLSG and LSIG 5 6 GROUND FAULT TIME SETTINGS The ground faul...

Page 13: ...MS 310 Trip Units derive their operating power from the phase currents and not from the neutral current passing current through the neutral sensor will not properly test the ground fault feature Figur...

Page 14: ...ULT TRIP UNIT ANY TEMPORARY CONNECTION MADE FOR THE PURPOSE OF CONDUCTING TESTS SHOULD BE RESTORED TO PROPER OPERATING CONDITIONS BEFORE RETURNING THE BREAKER TO SERVICE CAUTION Polarity Marks Current...

Page 15: ...mary cur rent carrying conductors used with the breaker must be sized to correspond with the maximum setting of the rat ing plug in accordance with National Electrical Code requirements The Long Delay...

Page 16: ...Lockout Switch and Terminal Block GFAU Ground Fault Alarm Unit Trip Unit Functions 3 POLE 4 POLE KES3125LS KES3125LSI KES3125LSG KES3125LSIG KES4400LS KES4400LSI KES4400LSE KES4400LSIE KES3250LS KES32...

Page 17: ...In 250A 125A 150A 200A 250A In 125A 160A 225A 250A In 400A 200A 250A 300A 400A In 200A 250A 315A 400A In 250A 300A 350A 400A In Short Delay Pick up In multiples of installed rating plug amperes Adjust...

Page 18: ...on Leaflet IL29C614F Effective December 2011 Instructions forThe Digitrip RMS 310 3 Pole and 4 PoleTrip Unit Installation and Operation with K Frame Series C Circuit Breakers EATON CORPORATION www eat...

Page 19: ...on Leaflet IL29C614F Effective December 2011 Instructions forThe Digitrip RMS 310 3 Pole and 4 PoleTrip Unit Installation and Operation with K Frame Series C Circuit Breakers EATON CORPORATION www eat...

Page 20: ...information is required you should consult an authorized Eaton sales representa tive The sale of the product shown in this literature is subject to the terms and conditions outlined in appropriate Eat...

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