Compact Merlin Gerin - STR

 

Functions and  characteristics 

Compact NS400 to 630 circuit breakers, types N, H and L, 3-pole and 4-pole, may  be equipped with any of the STR23SE, STR23SV, STR53UE and STR53SV  electronic trip units.

Protection of distribution systems STR trip units for Compact NS400 to 630

60

40

      6       1       1       5       0       1       B       D

250

400

500

600

STR23SE / STR53UE STR23SE 0SN STR23SE / STR53UE

STR23SV / STR53SV? ?

The and of STR53SV trip units  offerSTR53UE a wider range settings and the  STR53UE offers a number of optional  protection, measurement and  communications functions.

Standard protection with selectivity 

Protection of systems with an  overloaded neutral  Protection of systems U > 525 V 

Protection of systems supplied  by generators. Protection of long cables 

Selection of the trip unit depends on the type of distribution system protected and the operational voltage of the circuit breaker. Protection for all types of circuits, from 60 to 630 A, is possible with only five tripunit catalogue numbers, whatever the circuit-breaker operational voltage: b U y 525 V: STR23SE, STR23SE OSN or STR53UE b U > 525 V: STR23SV or STR53SV. Trip units do not have a predefined rating. The tripping threshold depends on the circuit breaker rating and the LT (long time) current setting. For example, for an STR23SE trip unit set to the maximum value, the tripping threshold is: v 250 A, when installed on a Compact NS400 250 A v 630 A, when installed on a Compact NS630.

STR23SE (U y 525 V) and STR23SV (U > 525 V) electronic trip units 6

1

7

3

t

      1       5       7       3       0       1       B       D

1

STR 23 SE

      4       9       0       4       2       E

2

Io .8

.9

.7

3

.93 .95 .98

.8 x In

+

.88

Isd

.85

.5

4

.9 1

.63

90 %Ir 105

alarm

Ir

1

5

6

4

7

3

8

2

x Io

10 x Ir

Ir

-

Isd

5 test

0

 

1

long-time threshold (overload protection) Ir  long-time tripping delay  short-time pick-up (short-circuit protection) Isd  short-time tripping delay  instantaneous pick-up (short-circuit protection) Ii  test connector  percent load indication 

2  3  4  5  6  7 

Ir 

Isd  

li

 

I

Protection The protection functions may be set using the adjustment dials. Overload protection Long-time protection with an adjustable threshold and fixed tripping delay: b Io base setting (6-position dial from 0.5 to 1) b Ir fine adjustment (8-position dial from 0.8 to 1). Short-circuit protection Short-time and instantaneous protection: b short-time protection with an adjustable pick-up and fixed tripping delay b instantaneous protection with fixed pick-up. Protection of the fourth pole On four-pole circuit breakers, neutral protection is set using a three-position switch to 4P 3d (neutral unprotected), 4P 3d + N/2 (neutral protection at 0.5 In) or 4P 4d (neutral protection at In). Protection of an overloaded neutral (OSN): For 4-pole circuit breakers, special protection of systems with high 3rd order harmonic contents. In position 4P 4d, the switch sets the neutral protection threshold to 1.6 x Ir.

Indications A LED on the front indicates the percent load: b ON - load is > 90 % of Ir setting b flashing

- load is > 105 % of Ir setting.

Test A mini test kit or a portable test kit may be connected to the test connector on the front to check circuit-breaker operation after installing the trip unit or accessories.

A-12