Schneider Electric Class 615 dimensions Electronic Trip Unit STR53UP, Protection, Self-monitoring

Compact® NSF and NSJ 150 to 600 A Circuit Breakers

Section 4—Trip Units

Electronic Trip

Unit STR53UP

06153067

81

2	3	4	5	6	9
STR 53 UP			>	>	>

t

7

1

2

6

%Ir Ir Isd Ig

7

Io

.8 .9

.7 1

.6

.5 1

x In

test

+-

Ir

.88.90 .93	.95
.85	.98
.8	1

x Io

tr	8
4
2
0,5	8

(s) @ 6 Ir

Isd

4 5

36

2 7

1.57

x Ir

tsd	.3 .3
(s).2		.2
.1		.1
0		0
o n	I2 t	o ff

Ii

4	6
3	8
2	9
1.5	9

x In

Ig

.5	.6
.4	.7
.3	.8
.2	1

x In

tg	.4 .4
(s) .3		.3
.2		.2
.1		.1
	I2 t
o n		o ff

				A
				tr
				tsd
In	I1	I2	I3	Ir	Isd li

3

4

5

0

Ir Isd I I

Protection	• Long-time (LT) overload protection, adjustable threshold, based on actual rms current, as defined
	by IEC 947-2, appendix F
	— Adjustable threshold (1) using six lo base settings (0.5–1) and fine adjustment Ir with eight
		settings ranging from (0.8–1)
	— Adjustable tripping time (2)
	• Short-time (ST) short-circuit protection
	— Adjustable threshold Isd (3)
	— Adjustable time delay (4), with or without constant I2t function
	• Instantaneous (Ii) short-circuit protection, adjustable threshold (5)
	• Neutral protection available on standard four-pole circuit breakers; protection level controlled using
	three-position switch
	—	4P	3D: no protection
	—	4P	3D + N/2: neutral protection at 0.5 Ir
	—	4P	4D: neutral protection at Ir

Overload Indications (%Ir)

Fault Indications

•LED (9) lights solid when current exceeds 0.9 Ir

•LED (9) flashes when current exceeds long-time threshold Ir

LEDs indicate the type of fault that caused tripping:

•Overload (LT protection) or abnormal component temperature (>Ir)

•Short-circuit (ST or instantaneous protection) (>Isd)

•Ground-fault (if earth-fault protection option is present) (>Ig)

•Microprocessor malfunction—both (>Ir) and (>Isd) LEDs go on, plus the (>Ig) LED, if the ground- fault protection option is present

The LEDs are battery powered with spare batteries supplied in the adapter box. When a fault occurs, the LED indicating type of fault shuts off after approximately 10 minutes to conserve battery power. The fault data is stored in memory and the LED can be re-illuminated by pressing the battery/LED test button (9). The LED automatically goes off and memory is cleared when the circuit breaker is reset.

Test	•	Test connector in front (8) for connection to test kit (see page 16); used to check circuit breaker
		operation after fitting trip unit or other accessories
	•	Test button (9) for (%Ir), (>Ir), (>Im) and (>Ig) LEDs and battery
Self-monitoring	The circuit breaker trips for both microprocessor faults and abnormal temperatures.

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