I-10
Motor Protection Circuit Breaker
J7MN
Descriptions
Releases
Circuit-breakers J7MN are equipped with bimetallic-based, inverse-
time delayed overload releases and with instantaneous overcurrent
releases (electromagnetic short-circuit releases). The overload
releases can be set in accordance with the load current. The over-
current releases are permanently set to a value 13 times the rated
current and thus enable trouble-free start-up of motors. The scale
cover can be sealed to prevent unauthorized adjustments to the set
current.
Operating mechanisms
Circuit-breakers J7MN-3P are actuated via a rocker operating mech-
anism and circuit-breakers J7MN-3R, J7MN-6R and J7MN-9R via a
rotary operating mechanism. An electrical signal can be output, at all
Circuit-breakers, via a signalling switch to indicate that the Circuit-
breaker has tripped. All operating mechanisms can be locked in the
0 position with a padlock (shackle diameter 3.5 to 4.5 mm). The
J7MN Circuit-breakers fulfil the isolation characteristics specified in
IEC 60947-2.
Operating conditions
Circuit-breakers J7MN are suitable for use in any climate. They are
designed for operation in enclosed rooms under normal conditions
(e. g. no dust, corrosive vapours or harmful gases). Suitable enclo-
sures must be provided for installation in dusty or damp rooms. Cir-
cuit-breakers J7MN can also be fed from below. In order to prevent
premature tripping due to phase failure sensitivity, the three conduct-
ing paths must always be uniformly loaded. The conducting paths
must be connected in series in the case of single-phase loads.
Short-circuit protection
The short-circuit releases of J7MN circuit-breakers disconnect the
faulty load feeder from the system in the event of a short circuit and
thus prevent any further damage from being caused. Circuit-break-
ers with a short-circuit breaking capacity of 50 kA or 100 kA at a volt-
age of 400 V AC are practically short-circuit-proof at this voltage, as
higher short-circuit currents are not usually encountered at the instal-
lation point. Back-up fuses are only necessary if the short-circuit cur-
rent at the installation point exceeds the rated ultimate short-circuit
breaking capacity of the circuit-breakers.
Motor protection
The tripping characteristics of J7MN circuit-breakers are designed
mainly to protect three-phase induction motors. The circuit-breakers
are therefore also referred to as Manual Motor Starters. The current
of the motor to be protected is set with the aid of the scale.
Line protection
J7MN Circuit-breakers for motor protection are also suitable for line
protection. The J7MN Circuit-breakers fulfil the isolation conditions of
IEC 60 947-3 as well as the additional test conditions for circuit-
breakers with isolation characteristics specified in IEC 60947-2. Tak-
ing IEC 60 204-1 into consideration, they can thus be implemented
as main and EMERGENCY STOP switches. Door-coupling rotary
operating mechanism do not fulfil the isolation characteristics.
Wiring diagrams
J7MN-6R
J7MN-9R + J77MN-TB100
Rated operational current
Ie
26
32
40
50
63
63
75
90
100
A
Max. short-circuit current
240 V
100
100
100
100
100
100
100
100
100 kA
480 V
50
50
50
50
50
40
40
40
40 kA
600 V
10
10
10
10
10
10
10
10
10 kA
Motor load
1-phase
115 V
2
3
3
5
5
5
7
1
/
2
10
10 HP
230 V
5
5
7
1
/
2
10
15
15
15
20
20 HP
Motor load
3-phase
230 V
10
10
15
15
20
25
25
30
40 HP
460V
20
25
30
40
50
50
60
75
75 HP
600V
25
30
40
50
60
60
75
100
100 HP
Max. rated fuse or breaker
600
600
600
600
600 1,000 1,000 1,000 1,000 A
Combination Motor Controller Type E
Ratings of auxiliary switches and
alarm switches
Lateral auxiliary switch with
J77MN-xxS and signalling
switch J77MN-T
Transversal auxiliary switch
with J77MN-xxF
Breaking capacity
A600
A300
AC
Q300
R300
DC
Circuit breakers
Traverse Aux. Contact blocks
Aux. Contact Block (side mounted)
J7MN
J77MN-11F
J77MN-20F
J77MN-02F
J77MN-11S
J77MN-20S
J77MN-02S
Alarm Switch
Undervoltage Release
Shunt Release
J77MN-T-11S
J77MN-TA-11S
J77MN-U-...
J77MN-S-...
