Eaton and Moeller DILM Contactors, ZB Overloads and PKZM, New Zealand

Eaton and Moeller / Contactors and motor protection

A contactor part number is two things joined together: a frame and a coil voltage. DILM9 is the frame. What follows in brackets is the coil, and a 230 V coil on a 24 V control circuit does nothing while a 24 V coil on 230 V destroys itself. The frame is what people copy and the coil is what people get wrong.

DILM contactors, ZB overloads and PKZM motor protective switches are the core of most Moeller-built motor starters, and between them they cover most of what we are asked for on this brand.

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Reading a contactor part number

Field	Means
DILM	The contactor range
The number after it	The frame, broadly the current rating
A suffix such as -10	Built-in auxiliary contacts
The bracketed part	The coil voltage and frequency

So the same frame exists in a long list of coil voltages, and the physical contactor looks identical in all of them.

The coil is where orders go wrong

Mistake	Result
Coil rated higher than the control supply	Will not pull in, or chatters
Coil rated lower than the control supply	Overheats and fails, sometimes quickly
AC coil on a DC control circuit	Will not work correctly
Right voltage, wrong frequency band	Marginal operation

Panels commonly mix 24 V DC, 110 V AC and 230 V AC control circuits, sometimes within the same enclosure, so do not assume from another contactor nearby.

Read the coil voltage off the device itself. It is printed on the contactor, and it is the field most often left out of an enquiry.

A chattering contactor is usually not the contactor

Symptom	Usually
Buzzing or chattering	Low control voltage, a poor connection, or dirt in the magnet faces
Drops out under load	Control supply sagging when other coils pull in
Will not pull in at all	Coil, control circuit or an interlock
Pulls in but the motor does not run	Main contacts, or the supply to them
Contactor hot	Loose terminations, or undersized for the duty

Measure the control voltage at the coil terminals while it is trying to pull in, not at the transformer. A supply that reads correctly at rest and collapses under load produces exactly this symptom, and a new contactor does the same thing.

Auxiliary contacts are separate parts

Contactors carry a small number of auxiliary contacts built in, and more are added with clip-on blocks.

Type	Notes
Built-in auxiliaries	Indicated in the contactor's own part number
Front-mounting blocks	Clip onto the face
Side-mounting blocks	Clip to the sides, where the front is occupied
Suppressors	RC and varistor modules for the coil
Mechanical interlocks	For reversing pairs. A separate part

So a replacement contactor may need blocks moved across or ordered. Count the auxiliary contacts wired on the old one before it comes out, and note whether they are front or side mounted.

On a reversing starter, the mechanical interlock between the two contactors matters. It is what physically prevents both closing together, and it is a separate item that is easy to leave off an order.

Overloads are matched to the contactor

A ZB overload relay mounts directly onto the contactor, taking its main connections from the contactor's output terminals. That makes it frame specific.

Must match	Why
The contactor frame	Physically and electrically, it bolts on
The motor current	The adjustment range must bracket the full load current
The starting method	Direct on line and star delta are set differently

So an overload is quoted against the contactor and the motor, not on its own. Send both numbers and the motor nameplate.

Setting it

The dial is set to the motor's full load current, and that number comes off the motor nameplate rather than being estimated.

Symptom	Check
Trips after running a while	Setting too low, or the motor genuinely overloaded
Never trips, motor burns out	Setting too high
Trips on starting	Starting duty, or the wrong class of overload
Trips in summer only	Panel temperature. Thermal overloads are ambient sensitive

That last one catches people. A thermal overload responds to its own temperature as well as the motor current, so a hot panel makes it trip earlier. If a starter trips only on warm days and only in one enclosure, look at the panel before the motor.

Electronic overloads are less ambient sensitive and offer wider adjustment ranges, which is worth considering on a starter that has been a repeat problem.

PKZM motor protective circuit breakers

A PKZM does two jobs in one device: overload protection for the motor and short circuit protection for the circuit. That is why it appears instead of a separate breaker and overload.

The setting range is in the part number

Point	Detail
The trailing figure is the top of the range	The device adjusts up to it
The range must bracket the motor current	Not sit above or below it
Ranges overlap between devices	So more than one part number can suit a given motor

So a motor drawing a current near the top of one device's range and the bottom of another's is better on the one where it sits comfortably in the middle. Sitting at the extreme of an adjustment range gives less useful protection.

Send us the motor nameplate current and we will pick the range rather than just matching the old part number, which may itself have been wrong.

Accessories

Accessory	Purpose
Auxiliary contact blocks	Status to the control circuit or PLC
Trip indicating contacts	Distinguishes a trip from a manual switch off
Shunt and undervoltage releases	Remote tripping
Link kits	Joins the device to a contactor as a starter assembly
Enclosures and door couplings	For surface mounting or door operation

The trip indicating contact is the useful one. Without it the control system cannot tell the difference between somebody switching a motor off and the protection tripping, which matters for alarms and for fault finding.

Link kits are commonly forgotten. Where the motor protective switch and the contactor are joined into a compact starter, that connection is a part.

What is actually replaceable

Failed	Often
Coil burnt out	On larger frames the coil is a separate part
Main contacts worn or welded	On larger frames, a contact kit
Auxiliary contact not making	The auxiliary block
Small frame contactor failed	Usually the whole device. Parts are not economic
Overload tripping wrongly	Setting, or the ambient, before the device

The dividing line is frame size. On small contactors a replacement is cheaper than parts and labour. On larger frames coils and contact kits are genuinely worth fitting, and a welded main contact does not mean scrapping a large contactor.

Tell us the frame and what failed and we will say which side of that line you are on.

Star delta and reversing assemblies

Arrangement	Parts involved
Direct on line	One contactor, one overload or motor protective switch
Reversing	Two contactors, a mechanical interlock, wiring kit
Star delta	Three contactors, a timer, interlocks and a wiring kit

On a star delta starter the three contactors are not all the same size, because they carry different currents in the star and delta configurations. So replacing one means matching that position, not copying whichever contactor is easiest to read.

Photograph the whole starter before removing anything. It captures all three part numbers, the interlocks and the wiring arrangement in one image.

Before ordering a replacement

Symptom	Check first
Chattering or buzzing	Control voltage measured at the coil under load
Coil failed quickly after fitting	Coil voltage against the control supply
Overload trips on warm days only	Panel temperature
Trips on starting	Starting duty and overload class
Motor burnt out with no trip	Overload setting against the nameplate
New contactor fitted, control circuit incomplete	Auxiliary blocks not moved across
Reversing starter allows both directions	Mechanical interlock missing
Large contactor with welded contacts	A contact kit may be available

What to send us

The full part number including the coil voltage.

The motor nameplate current and voltage.

The starting method. Direct on line, reversing or star delta.

A photo of the starter in the panel, showing overloads, auxiliary blocks and interlocks.

The control circuit voltage.

What failed, because a coil, a contact kit or an auxiliary block may be the answer.

What we can supply

Contactors. DILM across the frames and coil voltages, DILA control relays, and the earlier DILEM and DIL00M ranges.

Overloads. ZB thermal and ZEB electronic, matched to the contactor frame and motor current.

Motor protection. PKZM and PKE motor protective circuit breakers across the setting ranges, with auxiliary and trip indicating contacts.

Accessories. Auxiliary blocks front and side mounting, suppressors, mechanical interlocks, link kits, wiring kits and enclosures.

Repair parts. Coils and contact kits for the larger frames.

Complete starters. Where you would rather have the assembly quoted as a set, including the parts people forget.

A sensible motor control spares holding

Item	Why
One contactor per frame and coil voltage you run	Most plants use only two or three combinations
Auxiliary contact blocks	Cheap, and easy to be caught without
Coils for the larger frames	Cheaper than the contactor
One overload per common range	They fail less than contactors but stop the same motor
A photo of every starter	Free, and it captures the whole arrangement

Motor control spares are unusually cheap against the downtime they cover, and a plant typically runs a handful of frame sizes rather than dozens.

We buy Eaton and Moeller motor control

Contactors, overloads and motor protective switches from stripped panels resell steadily.

Keep overloads on the contactors they were mounted on, leave auxiliary blocks in place, and keep interlocks and link kits with their starters. Matched assemblies are worth more than loose devices. 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.

Why do you need the coil voltage?
Because the same contactor frame comes in many coil voltages and they look identical.

My contactor chatters.
Measure the control voltage at the coil while it tries to pull in. It is usually the supply, not the contactor.

Why does the overload only trip in summer?
Thermal overloads respond to ambient temperature as well as motor current. Look at the panel.

How do I pick a PKZM?
By the setting range bracketing the motor's full load current, ideally with the motor sitting mid range.

Can I replace just the coil?
On larger frames usually yes. On small frames a new contactor is normally cheaper.

Do you supply used equipment?
Where a part is obsolete. A lot of Moeller motor control is still current under the Eaton name, and then we quote new.

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 part numbers

With the coil voltage and the motor nameplate current. Those two figures settle most of a motor control enquiry. Quotes in NZD including GST.

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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 Eaton. Eaton and Moeller are trademarks of Eaton Corporation. All trademarks, brand names and part numbers are the property of their respective owners and are used here for identification purposes only.