Danfoss VLT AutomationDrive FC-301 and FC-302, New Zealand

Danfoss / VLT AutomationDrive FC-301 and FC-302

Four option slots, and what is in them is not in the drive. A replacement FC-302 arrives without the fieldbus card, without the encoder card and without the relay card, and it will run a motor while talking to nothing.

The VLT AutomationDrive is the Danfoss machine building range and the one we are asked for most. FC-302 is the full version and FC-301 is the reduced one.

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FC-301 against FC-302

Establish this first, because the numbers are one digit apart and the drives are not equivalent.

Capability	FC-301	FC-302
Open loop VVC+ control	Yes	Yes
Flux vector, closed loop	No	Yes
Encoder feedback	No	Yes
Safe Torque Off, terminal 37	No	Yes
Permanent magnet motor control	Limited	Yes
Digital and analogue terminal count	Fewer	More
Positioning with MCO 305	No	Yes

Terminal 37 is the test. If the machine's safety circuit lands on terminal 37, the drive is providing an assessed safety function and an FC-301 cannot do it.

And if there is an encoder cable going into the drive, it is an FC-302 with an encoder option. Both facts are visible from the front without a manual.

Whether a substitution is valid on a safety circuit belongs with whoever holds the machine's safety assessment. We supply what you specify.

The four option slots

The most important commercial content on this page, because this is where replacement orders go wrong.

Slot	Takes	Family
A	Fieldbus	MCA
B	I/O, encoder, relay, sensor	MCB
C0 and C1	Motion control and functional extensions	MCO, MCF
D	24 V DC backup	MCB 107

Slot A, fieldbus

Option	Network
MCA 101	PROFIBUS DP
MCA 104	DeviceNet
MCA 120	PROFINET
MCA 121	EtherNet/IP
MCA 122	Modbus TCP
MCA 124	EtherCAT

The Ethernet based options all use RJ45 and look identical from the front. A PROFINET card and an EtherNet/IP card are different parts, and the drive will show a bus fault rather than anything more helpful.

Modbus RTU over RS485 is built in and needs no card. So a drive on plain Modbus serial has an empty slot A, correctly.

Slot B, I/O and feedback

Option	Function
MCB 101	General purpose I/O expansion
MCB 102	Encoder input
MCB 103	Resolver input
MCB 105	Relay card, additional relay outputs
MCB 112	PTC thermistor card, for motors in hazardous areas
MCB 113	Extended relay card
MCB 114	Sensor input, temperature sensors

Two of these are not optional in practice

MCB 102 encoder and MCB 103 resolver are what make closed loop work. Without the card the drive cannot read the feedback device, and a positioning or torque application will not run.

Encoder and resolver are different cards and not interchangeable. They are different feedback principles. Look at what the motor has before ordering.

MCB 112 is a certified motor protection function, used where the motor sits in a hazardous area and its thermistor has to be monitored to a standard. That is not a convenience feature and a drive without it does not provide the protection.

The 24 V backup option is worth knowing about

A specific and useful one.

MCB 107 supplies the control card from an external 24 V source, so the drive keeps its control electronics and its fieldbus connection alive when the mains drops.

Without it	With it
Mains drop takes the drive off the network	The PLC keeps talking to the drive
Diagnostics lost at the moment they matter	The fault is visible from the SCADA

So on a plant where drives disappear from the network during a supply dip, that is the option that was specified for it. A replacement without it behaves differently and it is not a fault.

Cards move across, or they go on the order

Option cards are physically transferable between drives of the same family. On a straight replacement the cards come out of the old drive and go into the new one, which is usually the cheapest route.

But a used drive bought without cards will not do the job, and a new drive quoted without them is an incomplete quote.

Tell us what is in the slots, or send a photo with the front cover off. The cards are labelled.

The Smart Logic Controller

The gotcha that catches people who assume a drive only follows orders.

The FC range includes a Smart Logic Controller, a small programmable logic function inside the drive, configured in the 13 parameter group. It runs comparators, timers and state logic on events the drive can see.

What it is used for
Simple sequences without a PLC
Pump alternation, level control, protection interlocks
Reacting to a fault faster than the PLC scan

So a machine may have logic living in the drive and nowhere else. A replacement drive at default parameters has none of it, and the symptom is a machine that runs but does not sequence.

That is a strong argument for a parameter backup, because the Smart Logic configuration goes with it.

The parameter groups

Useful for troubleshooting, because the group number tells you where to look.

Group	Covers
0	Operation and display, language, panel setup
1	Load and motor. Motor data and auto tune
2	Brakes. DC brake, mechanical brake, brake resistor
3	References and ramps
4	Limits and warnings
5	Digital inputs and outputs
6	Analogue inputs and outputs
7	PID controllers
8	Communications
13	Smart Logic Controller
14	Special functions, switching frequency, mains monitoring
15	Drive information. Hours run, kWh, fitted options, software version
16	Data readouts, live values

Group 15 tells you what the drive actually is

Genuinely useful on a used or unlabelled unit.

Group 15 reports the fitted option cards, the software version, the operating hours and the run hours, read straight off the panel.

So if the rating label has been destroyed by a wet plant, power the drive up and read group 15 rather than guessing. It also tells you the real age of a used drive, which the invoice date does not.

Automatic Motor Adaptation

The commissioning step that gets skipped, and then the drive gets blamed.

AMA measures the motor's electrical characteristics so the drive can control it properly. It is run from the 1 parameter group after the motor nameplate data is entered.

Type	Requires
Full AMA	Motor uncoupled from the load
Reduced AMA	Can be run with the load connected, less accurate

A replacement drive that runs roughly, trips under load or holds poor torque at low speed has often not had an AMA run. That costs nothing to check and it is not a hardware fault.

On a long motor cable or an unusual motor, the full AMA matters more.

Common alarms and what they usually mean

The alarm number is on the display and it narrows the job considerably.

Alarm	Meaning	Usually
4	Mains phase loss	Supply side. Fuse, contactor or incoming terminal
7	DC over voltage	Braking. Ramp too fast, or no brake chopper and resistor
8	DC under voltage	Supply dip or a mains phase issue
13	Over current	Mechanical load, or motor data and AMA
14	Earth fault	Motor or motor cable, more often than the drive
29	Heatsink temperature	Fan or blocked airflow. Both serviceable
30, 31, 32	Motor phase U, V or W missing	Motor cable, terminal or the motor winding
38	Internal fault	The drive itself

Note how many of these are not the drive. Earth fault, motor phase missing and heatsink temperature all point outward, and alarm 7 usually points at the braking arrangement.

Send us the alarm number with the part number. If the answer is a fan or a brake resistor we will say so rather than quoting a drive.

Frame size decides more than the footprint

What frame size affects
DC link discharge time before it is safe to touch
Whether a mains choke or DC choke is built in
Available enclosure and IP options
Fan arrangement and whether the fan is field replaceable
Mounting, cable entry and clearance requirements

Discharge time grows with frame size. Small frames are a few minutes and the largest are considerably longer. Isolating the supply does not make the drive safe. Wait the time specified for that frame, then measure the DC link before working on it.

Danfoss publishes the figure per frame. If you tell us the drive, we will tell you the number.

Before ordering a replacement

Symptom	Check first
Alarm 7 on stopping	Brake chopper and resistor, and the ramp time
Alarm 29	The fan. A separate part
Alarm 14	The motor and motor cable, before the drive
Runs rough or trips under load after a swap	Motor data and AMA
Machine runs but does not sequence	Smart Logic Controller. Logic lived in the old drive
Fieldbus dead after a swap	The slot A card. It does not come with the drive
Positioning will not work	The MCB 102 or MCB 103 feedback card
Safety circuit will not reset	Terminal 37, and whether the drive is a 302
Label unreadable	Read parameter group 15

What to send us

The full type code. It carries power, voltage, enclosure, filter class, brake chopper and coating.

Whether it is a 301 or a 302, and whether terminal 37 is used.

What is in the option slots, and whether you need them supplied or are moving them across.

The alarm number, if the drive is faulting.

Whether there is a braking resistor in the panel.

Whether you have a parameter backup.

A photo of the rating label, and one with the cover off showing the cards.

What we can supply

Drives. FC-301 and FC-302 across the frame sizes, voltage classes and enclosure ratings, with or without brake chopper and coating.

Option cards. MCA fieldbus, MCB I/O, encoder, resolver, relay and sensor cards, MCB 107 backup and MCO motion options.

Panels. LCP 101 and LCP 102, and the blanking plate for drives operated remotely.

Parts rather than whole drives. Cooling fans, braking resistors and control cards.

Used and surplus units are powered up and tested before they ship. On a drive that has been stored a long time we tell you, because the DC link capacitors matter.

We buy FC-301 and FC-302

AutomationDrive units hold value, and the option cards are worth real money on their own.

If you are stripping a machine, leave the cards in the slots and keep the LCP with the drive. A drive with a PROFINET card and a graphic panel is worth considerably more than a bare unit. See Sell To Us.

Common questions

Can you get a part that is not listed on your site?
Usually. The site shows what we hold, not what we can source.

Will my option cards fit the new drive?
Within the same family, generally yes. Tell us both type codes and we will confirm.

Is an FC-301 cheaper than an FC-302?
Yes, and it is also a different drive. No encoder feedback and no Safe Torque Off.

My drive keeps tripping on alarm 29.
Start with the fan and the airflow. We supply fans separately.

Can I read the specification off a drive with no label?
Yes. Power it up and read parameter group 15.

Do you supply used equipment?
Yes, where new is not available, tested and clearly described.

What is the lead time?
Ex stock items ship the next working day within New Zealand. We give you a firm lead time with the quote.

Do you quote in NZD?
Yes, in NZD including GST for New Zealand customers.

Send us your type codes

Tell us what is in the option slots. That is the difference between a drive that works and a drive that runs a motor while talking to nothing. Quotes in NZD including GST.

Request a quote

Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with Danfoss. Danfoss, VLT and AutomationDrive are trademarks of Danfoss A/S. PROFIBUS and PROFINET are trademarks of PROFIBUS Nutzerorganisation. EtherCAT is a trademark of Beckhoff Automation. EtherNet/IP is a trademark of ODVA. All trademarks, brand names and type codes are the property of their respective owners and are used here for identification purposes only.