POWER CIRCUITS
6.2
Bypass Contactor
Some EMX3 soft starters are internally bypassed and do not require an external bypass contactor.
Non-bypassed soft starters may be installed with an external bypass contactor. Select a contactor with an AC1 rating greater than
or equal to the full load current rating of the connected motor.
Internally bypassed models:
EMX3-0023B, EMX3-0043B, EMX3-0050B, EMX3-0053B, EMX3-0076B, EMX3-0097B, EMX3-0100B, EMX3-0105B, EMX3-0145B,
EMX3-0170B, EMX3-0200B, EMX3-0220B, EMX3-0255B, EMX3-0350B, EMX3-0425B, EMX3-0500B, EMX3-0580B, EMX3-0700B,
EMX3-0820B, EMX3-0920B, EMX3-1000B
Non-bypassed models:
EMX3-0255C, EMX3-0360C, EMX3-0380C, EMX3-0430C, EMX3-0620C, EMX3-0650C, EMX3-0790C, EMX3-0930C, EMX3-1200C,
EMX3-1410C, EMX3-1600C
6.3
Main Contactor
A main contactor must be installed if the EMX3 is connected to the motor in inside delta format and is optional for in-line connection.
Select a contactor with an AC3 rating greater than or equal to the full load current rating of the connected motor.
6.4
Circuit Breaker
A shunt trip circuit breaker may be used instead of a main contactor to isolate the motor circuit in the event of a soft starter trip. The
shunt trip mechanism must be powered from the supply side of the circuit breaker or from a separate control supply.
6.5
Power Factor Correction
If power factor correction is used, a dedicated contactor should be used to switch in the capacitors.
To use the EMX3 to control power factor correction, connect the PFC contactor to a programmable relay set to Run. When the motor
reaches full speed, the relay will close and power factor correction will be switched in.
CAUTION
Power factor correction capacitors must be connected to the input side of the soft starter. Connecting power factor
correction capacitors to the output side will damage the soft starter.
6.6
Short Circuit Protection Devices (SCPD)
Fuses may be installed to protect the soft starter or the installation.
Type 1 Coordination
Type 1 coordination requires that, in the event of a short circuit on the output side of a soft starter, the fault must be cleared without
risk of injury to personnel. There is no requirement that the soft starter must remain operational after the fault.
HRC fuses (such as Ferraz/Mersen AJT fuses) can be used for Type 1 coordination according to IEC 60947-4-2 standard.
Type 2 Coordination
Type 2 coordination requires that in the event of a short circuit on the output side of a soft starter, the fault must be cleared without
risk of injury to personnel or damage to the soft starter.
Semiconductor fuses for Type 2 circuit protection are additional to HRC fuses or MCCBs that form part of the motor branch circuit
protection.
CAUTION
Adaptive Control controls the motor's speed profile, within the programmed time limit. This may result in a higher level
of current than traditional control methods.
CAUTION
DC Brake: A high brake torque setting can result in peak currents up to motor DOL being drawn while the motor is
stopping. Ensure protection fuses installed in the motor branch circuit are selected appropriately.
CAUTION
Integral solid state short circuit protection does not provide branch circuit protection. Branch circuit protection must be
provided in accordance with the National Electrical Code and any additional local codes.
User Manual (710-04840-00M) |
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