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Littelfuse SE-325 Series User Manual

Protection relays & controls, Neutral-grounding-resistor monitoring, Neutral-grounding-resistor monitor description

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Protection Relays & Controls

© 2013 Littelfuse Protection Relays & Controls

Rev: 4-A-050213

Based on Manual Rev 12

Neutral-Grounding-Resistor Monitoring

SE-325 SERiES (PGM-8325)

Neutral-Grounding-Resistor Monitor

Description

The SE-325 Neutral-Grounding-Resistor Monitor is used on

resistance-grounded systems up to 25 kV to monitor the

integrity of the neutral-to-ground path and to detect ground

faults. It measures current and voltage in a transformer or

generator neutral-to-ground connection and continuity of the

neutral-grounding resistor (NGR). The SE-325 coordinates these

three measurements to detect a loose connection, corrosion,

ground fault, or NGR failure, and provides one alarm or trip

output contact.

ORdERiNG NuMbER

cONtROl POwER

SE-325

120 Vac

SE-325D

120 Vac/Vdc

SE-325E

240 Vac

Ordering Information

Simplified Circuit Diagram

NGR

L2

CT

L1

SE-325

SERIES

ER SERIES

(Sensing Resistor)

(NGR Monitor)

A

FEatuRES

bENEFitS

Continuous NGR

monitoring

Detects resistor failure within seconds, reduces

transient-overvoltage risk, removes risk of ground-

fault-detection failure

Ground-fault

Detection

Main or backup protection to detect a ground

fault anywhere on the monitored system

Adjustable pickup

(0.5 - 4 A)

Select greatest sensitivity without

false operation

Adjustable time delay

(0.1 - 2 s)

Adjustable trip delay allows system coordination

Output contacts

Form A output contact

Selectable contact

operating mode

Selectable fail-safe or non-fail-safe operating

modes allows connection to shunt or undervoltage

breaker coil or alarm system

Features & Benefits

B

accESSORiES

REquiREMENt

CT200 Series

Required

ER Series

Required

SE-MRE-600

Optional

Rk-325, Rk-325I, Rk-302

Optional

Rk-13

Optional

NGRM-ENC

Optional

Specifications

IEEE Device Numbers

Ground Fault (50G/N, 51G/N),

Overvoltage (59N), Lockout Relay (86),

Checking Relay (3)

Input Voltage

See ordering information

Dimensions

H 150 mm (5.9"); W 109 mm (4.3");

D 100 mm (4.0")

GF Trip Level Settings

0.5-4.0 A

GF Trip Time Settings

0.1-2.0 s

RF Trip-Level Settings

20-400 Vac (≤5 kV systems)

100-2,000 Vac (>5 kV systems)

Contact Operating Mode Selectable fail-safe or non-fail-safe

Reset Button

Standard feature

Output Contacts

Form A

Approvals

CSA certified,

UL Listed (E340889)

,

C-Tick (Australian)

Conformally coated

Standard feature

Warranty

5 years

Mounting Surface

CT200 Series Current Transformer
Required CT detects ground-fault current.

B

Accessories

A

ER Series Sensing Resistor

Required interface between the power

system and the SE-325. Eliminates

hazardous voltage levels at the monitor.

RK Series Remote Indication and Reset

Optional panel-mounted remote indication

and reset assemblies. Available in NEMA 1 or

NEMA 4 configurations.

Consult manual online for additional ordering options.

Littelfuse.com/se-325