RV4141A

PRODUCT SPECIFICATION

REV. 1.0.1 7/8/03

5

fier is its maximum of 200 µV, the trip current error is

±5.6%.

The SCR anode is directly connected to a solenoid or relay

coil. It can be tripped only when its anode is more positive

than its cathode. It must have a high dV/dt rating to ensure

that line noise (generated by electrically noisy appliances)

does not falsely trigger it. Also the SCR must have a gate

drive requirement less than 200 µA. C3 is a noise filter that

prevents high frequency line pulses from triggering the SCR.

The relay solenoid used should have a response time of 3 ms

or less to meet the UL 943 timing requirement.

Sense Transformers and Cores

The sense and ground/neutral transformer cores are usually

fabricated using high permeability laminated steel rings.

Their single turn primary is created by passing the line and

neutral wires through the center of its core. The secondary is

usually from 200 to 1500 turns.

Magnetic Metals Corporation

1900 Hayes Ave.

Camden, NJ 08105

(856) 964-7842

Is a full-line suppliers of ring cores and transformers

designed specifically for GFCI and related applications.

Determine the nominal ground fault trip current requirement.

This will be typically 5 mA in North America (117V AC)

and 22 mA in the UK and Europe (220V AC). Determine the

minimum delay time required to prevent nuisance tripping.

This will typically be 1 to 2 ms. The value of C2 required to

provide the desired delay time is:

C2 = 6 x T

where:

C2 is in nF

T is the desired delay time in ms.

rent specification is:

where:

Ω

T is the time delay in ms

P is the period of the line frequency in ms

N is the number of sense transformer secondary turns.

This formula assumes an ideal sense transformer is used.

30% to when using a non-ideal transformer.

R

SET

4.6

N

×

I

FAULT

COS 180

×

TP

⁄

()

---------------------------------------------------------------

=

Figure 1. GFI Application Circuit

Mov

Line

Sense Transformer

1:1000

5 Ring Steel Core

Phase

Neutral

Press to

Test

Grounded Neutral

1:200

Normally Closed

Latching Contacts

Load

Fault

Resistance

Not Part of

Application

RV4141A

Solenoid

20K

0.4

1.6

24K

1W

Q1

TAG

X0103DA

C3

10 nF

C2

12 nF

1

µF 35V

C4

1000 pF

C1

10 nF

1.1 Meg

470

+

1

2

3

4

8

7

6

5

GFCI

Note:

1. Portions of this schematic are subject to U.S. patents 3,878,435 and Re. 30,678.

15K

65-4141A-03

1N4004