
Operating Instructions – Explosion-Proof AC Motors DR63/eDR63, DVE250/280
33
5
Motors of category 2G, 2GD, 3D and 3GD
Electrical Installation
The following table shows the type of motor protection required according to the respec-
tive approval:
For permitted operating modes depending on the motor protection, see chapter "Permit-
ted operating modes". SEW-EURODRIVE equips brakemotors in category 3D and 3GD
with positive coefficient thermistors (TF).
5.14.6 Protection exclusively with motor protection switch
Note the following when installing the motor protection switch according to EN 60947:
•
For categories 2G and 2GD:
With starting current ratio I
A
/I
N
listed on the name-
plate, the response time of the motor protection switch must be less than the heating
time t
E
of the motor.
• The motor protection switch must disconnect all poles in the event of a phase failure.
• The motor protection switch must be approved by a notified body and assigned a cor-
responding inspection number.
• The motor protection switch must be set to the rated motor current indicated on the
nameplate. With category 2G and 2GD, the permitted nominal motor current is spec-
ified on the prototype test certificate.
5.14.7 Protection exclusively with PTC temperature sensors (TF)
The positive coefficient thermistor must be evaluated using a suitable device. Observe
the applicable installation regulations.
The PTC thermistors comply with DIN 44082.
Resistance measurement (measuring instrument with V
≤
2.5 V or I < 1 mA):
• Standard measured values: 20 – 500
Ω
, thermal resistance > 4000
Ω
The PTC thermistor (TF) is required in order to maintain a safe isolation and for thermal
monitoring.
The evaluation function of the temperature monitoring must be activated in connection
with the temperature sensor measuring circuit and must become effective in the event
of an overtemperature.
Category
2 (2GD / Gb Db or 2G / Gb)
3 (3GD / Gc Dc or 3G / Dc)
Operation:
Supply sys-
tem
Frequency
inverter
Supply sys-
tem
•
Frequency
inverter
•
Soft start
Pulsed
Designation
(see nameplate):
T
e
time
T
e
time
–
–
–
Motor protection via
A
B
A
B
B
CAUTION
Damage to the temperature sensor due to excessive voltage.
Possible destruction of the temperature sensor.
• Do not apply any voltages > 30 V