IEEE 1584 · Engineering
Motor Start Analysis Services in Spain | Carelabs Experts
Motor Start Analysis. A motor starting study calculates the voltage dip and acceleration time a large motor causes at startup, confirming your system can bring it up to speed without nuisance tripping, excessive running current, or instability elsewhere in the facility. Carelabs models across-the-line, autotransformer, reactor, and variable frequency drive starting methods to recommend the right one for your load.
Free ConsultationWhat happens in the first two seconds
A large motor draws several times its rated current while accelerating, and the voltage dip that results is felt by everything else on the busbar. The study establishes whether that is acceptable before the motor is bought.
What We Deliver
Voltage dip quantified across the network
Bus voltages are calculated through the acceleration period, so the dip is known at the starting motor and at every other bus. A start that is comfortable at the motor can still drop out contactors elsewhere on the installation.
WHY IT MATTERS
The motor starts. Everything else stops.
The usual symptom is not a motor that fails to start. It is a contactor dropping out on another line, a drive tripping on undervoltage or a control system resetting, every time one large machine is started.
- Dip assessed against the voltage tolerance of sensitive loads on the same busbar, not only against a generic limit at the point of supply.
- Transformer impedance taken from test certificates where available, since typical values shift dip results materially on a weak supply.
- Load torque characteristic established from the driven machine rather than assumed, because fans, pumps and conveyors behave very differently during acceleration.
- Repeated starting assessed where duty requires it, since thermal limits and not electrical ones usually govern how often a motor may be restarted.
- Generator-supplied starting modelled separately where standby supply exists, as generator impedance produces a substantially deeper dip than the utility.
DELIVERABLES
What you receive
Issued against REBT with the modelling assumptions, load characteristic and supply basis stated explicitly.
- 1Voltage dip profile at every bus through the acceleration period
- 2Acceleration time with the torque margin shown against the load curve
- 3Comparison of starting methods with the dip and torque consequence of each
- 4Protection settings that permit the start while still protecting the motor
- 5The calibrated ETAP model, so the next motor addition is assessed rather than assumed
How the study runs
Collect motor and load data
Nameplate data, starting characteristics and the driven machine's speed-torque and inertia characteristics are gathered, since the load governs the outcome as much as the motor.
Establish the supply
Source impedance is determined from the distribution company's fault level and transformer data, because dip depth is a function of supply strength.
Model the network
The network is built in ETAP with the motor represented dynamically rather than as a fixed load, which is what allows the acceleration to be simulated.
Simulate the start
Acceleration is simulated with voltage, current, torque and speed tracked throughout, under both utility and any standby supply arrangement.
Test the alternatives
Where the dip is unacceptable, starting methods are compared on the same model so the recommendation rests on simulation rather than on general preference.
Report and settings
Findings are issued with recommended starting arrangement and protection settings that accommodate the start without compromising motor protection.
Frequently asked questions
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