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Half‑Unit Withdrawable Drawer - The Highest-Density Functional Unit, 63A

Half‑Unit Withdrawable Drawer - The Highest-Density Functional Unit, 63A

1/2 unit withdrawable drawer for GCS, GCK and MNS switchgear. 63A, three-position isolation, silver-plated contacts, factory tested. CKD kits.

Overview
Applications
Technical Data
Services
Quality Control
Recommended Products

1/2 unit is the smallest standard drawer in the MOLDVOLT range and the one that decides how economic a withdrawable board actually is. Two units occupy one module position, so a section that would hold 9 single-unit feeders holds 18 half-unit feeders. On a distribution board with many small outgoing circuits, that difference is one cabinet section instead of two - less steel, less floor space, less cable, less money.

WHY DENSITY IS A COMMERCIAL ARGUMENT, NOT A TECHNICAL ONE
Switchroom floor area is expensive in every market we serve, and on retrofit projects it is often fixed. When a client is replacing an old fixed board inside an existing room, the ability to fit the required number of feeders in the available width is frequently what wins the order. Quote the half-unit configuration and you can offer a withdrawable board where a competitor can only offer fixed.

WHAT MAKES A DRAWER GOOD OR BAD
Everything that matters is at the interface. The isolating contacts must self-align and hold specified pressure, because a contact running slightly high in resistance heats, oxidises and eventually fails - typically two years after handover, and always at full load. The three-position mechanism must latch positively so that Test really is Test. And the earth contact must make before the power contacts and break after them, every single time.

These are the parts local workshops get wrong when they build their own drawers, and the failure is invisible on the day of commissioning. We supply the unit assembled, wired and individually tested, so what your workshop is building is a cabinet, not a mechanism.

INTERCHANGEABILITY IS THE POINT
Module dimensions are held to the same drawing revision year after year. A 1/2 unit ordered today fits a board built years ago. That is the reason consultants specify a standardised drawer system in the first place, and it is exactly what a builder loses when they design their own drawer in-house.

SUPPLIED READY OR AS A KIT
Built to your feeder schedule with your specified device brand, wired to terminals, labelled and tested. Or as a CKD kit - shell, isolating contacts, racking mechanism, interlock, handle, secondary plug and pre-cut wiring harness - with the assembly drawing, torque figures and gauge sheet. The pre-cut harness alone removes about 30% of assembly labour compared with cutting and crimping wire by wire.

Typical Applications

PRIMARY APPLICATIONS
- Small outgoing feeders on GCS and MNS distribution boards - lighting circuits, socket circuits, small plant supplies.
- Small motor starters up to approximately 15 kW in motor control centres.
- Sub-distribution board feeders in commercial buildings, hotels, hospitals and airports.
- Retrofit projects where feeder count is high and the existing switchroom cannot be enlarged.
- Water treatment and pumping stations with many small valve and dosing circuits.
- Process plants with a large number of low-power drives and instruments.
- Data centre and telecom facility distribution where circuit count is high.
- Solar PV plant auxiliary and tracker supply circuits.

TYPICAL CONFIGURATIONS
Distribution feeder with MCCB; direct-on-line motor starter with contactor, overload relay and control circuit; lighting contactor circuit with timer; metering circuit.

WHY BUYERS SPECIFY IT
A plant that can pull a failed feeder and slot a tested spare back in restores supply in minutes rather than hours. On continuous-process plants, downtime cost dwarfs the price difference between fixed and withdrawable construction - which is precisely the argument a panel builder should be making when the client pushes back on price.

REGIONAL FIT
- Middle East: high feeder counts in hotels, malls, hospitals and airports. Switchroom ambient of 50-55 C requires derating above the IEC +40 C reference. Spare-unit strategy is normally written into the specification on utility and EPC work.
- Africa: mining, water, agriculture and industry. Unstable grid conditions make an easily replaceable feeder unit genuinely valuable; a spare drawer is cheaper than a maintenance visit to a remote site.
- Russia and CIS: 380V/220V distribution, EAC under TR CU 004/2011 and TR CU 020/2011.
- Eastern Europe: 400V, CE under LVD and EMC to EN 61439-2.

NOT SUITABLE FOR
Feeders above the unit current rating - step up to 1 unit or larger. Fixed-type boards such as GGD, XL-21 and JXF, which have no drawer compartments.

Technical Data

TECHNICAL DATA - 1/2 Unit Withdrawable Functional Unit

Compliance: IEC 61439-1, IEC 61439-2, IEC 60947-2, GB 7251.1

Category	Item	Parameter Details
ELECTRICAL RATINGS	Rated operational voltage (Ue)	400 V / 415 V AC (380 V available)
	Rated insulation voltage (Ui)	1000 V
	Rated impulse withstand voltage (Uimp)	8 kV
	Rated frequency	50 Hz / 60 Hz
	Rated current of unit	63 A
	Rated short-time withstand of the assembly (Icw)	up to 80 kA for 1 s
	Rated conditional short-circuit current	determined by the fitted device
	Control voltage	230 V AC, 110 V AC, 24 V DC
MODULE GEOMETRY	Module size	half module width, one unit height
	Module height	1 unit height (2 units share one module position)
	Units per standard section	up to 36 half-units in a standard 1000 mm wide section, arrangement dependent
	Interchangeability	dimensionally identical across production batches and years
ISOLATING SYSTEM	Working Positions	Connect / Test / Disconnect, each positively latched with indication
	Primary contacts	silver-plated copper, spring-loaded, self-aligning
	Secondary contacts	silver-plated multi-pin plug, engages in Test position
	Earth contact	engages before and breaks after the power contacts
	Mechanical endurance	100,000 operating cycles
	Racking mode	manual handle racking, tool-free
INTERLOCKS	Interlock Functions	1. Drawer cannot be racked while the device is closed 2. Device cannot be closed between defined positions 3. Door cannot be opened with the device closed (defeatable by tool for authorised access) 4. Padlocking provision in the Disconnect position
FEEDER DEVICE	Applicable MCCB / Starter	MCCB frame up to 63 A, or contactor-based starter up to approximately 15 kW
	Feeder types	distribution feeder, direct-on-line starter, lighting contactor
	Motor protection	thermal overload relay or electronic motor protection relay
CONSTRUCTION	Shell Material	aluminium-zinc coated steel, powder coated
	Internal separation	Form 3b / Form 4b per IEC 61439-2 when installed
	Protection degree	IP30 to IP54 depending on cabinet configuration
	Wiring	pre-cut modular harness, ferruled and labelled, reducing on-site assembly labour by approximately 30% versus wire-by-wire termination
	Terminals	front accessible, sized for the feeder cable range
TESTING - EVERY UNIT	Factory Test Items	Dielectric withstand 1 minute at rated test voltage; insulation resistance recorded; three-position operation and interlock function verified; contact alignment and engagement gauged; functional test of the feeder logic
SERVICE CONDITIONS	Ambient temperature	-5 ℃ to +40 ℃ per IEC; verified to +55 ℃ with derating
	Relative humidity	50% at +40 ℃, up to 90% at +20 ℃
	Altitude	up to 2000 m

OPTIONS

NOTE
Two 1/2 units occupy a single module position, giving the highest feeder density in the range. This is the configuration to quote on retrofit projects where switchroom floor area is fixed.

Services

SUPPLIED READY TO INSTALL - THE HARD PART IS ALREADY DONE

A drawer is not a box with a breaker in it. Contact alignment, three-position interlock geometry and secondary plug engagement are the parts of a withdrawable board that local workshops get wrong, and a misaligned drawer is what turns into a burned contact two years later. We supply the units assembled, wired and tested, so your workshop is building a cabinet - not debugging a mechanism.

1. FUNCTIONAL UNITS BUILT TO YOUR SCHEDULE
Send us the feeder schedule and we build the drawers to it: distribution, direct-on-line, star-delta, soft starter, VFD, reversing. Device brand to your specification. Each unit is delivered wired to terminals, labelled and individually tested.

2. INTERCHANGEABILITY GUARANTEED ACROSS BATCHES
Standard module dimensions are held to the same drawing revision year after year. A 1-unit drawer ordered today fits a cabinet you built three years ago. This is the single reason consultants specify a standardised system, and it is where a proprietary in-house drawer design costs the client later.

3. CKD DRAWER KITS FOR LOCAL ASSEMBLY
If you would rather assemble in-house, we supply the drawer as a kit: shell, isolating contacts, racking mechanism, interlock, handle, secondary plug and wiring harness, with the assembly drawing and a torque and gauge sheet. The pre-cut modular wiring harness alone removes about 30% of on-site assembly labour compared with cutting and crimping wire by wire.

4. TRAINING ON THE MECHANISM
Alignment, contact pressure check, three-position verification, interlock function test and racking force check - taught on your own bench with your own units, on site or by video session.

5. SPARE DRAWERS AND SPARES STRATEGY
Quote the spare drawer set with the main order. A hot spare drawer is what lets a plant restore a feeder in minutes instead of hours, and on EPC projects it is often the reason a withdrawable board was specified in the first place. We keep the design available so spares remain buyable for the life of the installation.

6. DOCUMENTATION FOR YOUR SUBMITTAL
Routine test certificate per unit, device certificates, wiring diagram, drawer schedule and part list. Formatted so it drops straight into your IEC 61439 verification file.

7. AFTER-SALES
24-hour technical response, 12 months from commissioning or 18 months from shipment, spare contact and interlock parts held to the same revision.

8. COMMERCIAL TERMS
FOB, CFR, CIF, DDP, Ex-Works. Mixed loading with cabinets and components. Trade Assurance, T/T, L/C. Sample units accepted before volume.

Quality Control

QUALITY CONTROL - EVERY DRAWER TESTED AS A UNIT

A withdrawable board fails at the interface, not in the middle of a component. Contact pressure, alignment and interlock geometry decide whether the drawer is still healthy after a thousand operations, and none of that is visible after the door is closed. Each unit is therefore tested as a complete assembly before it leaves the line.

DIMENSIONAL AND MECHANICAL CHECKS - 100%
1. Shell dimensions and squareness against the module drawing, so interchangeability with earlier batches is real and not assumed.
2. Isolating contact alignment and engagement depth verified with a gauge; contact pressure measured against specification.
3. Silver plating thickness on primary and secondary contacts checked on batch samples.
4. Three-position operation - Connect, Test, Disconnect - each position confirmed to latch positively with correct indication.
5. Interlock function - the drawer cannot be racked with the device closed, and the device cannot be closed between defined positions. Tested in both directions.
6. Racking operating force measured and recorded; a stiff mechanism is rejected, not adjusted at the customer's site.
7. Earth contact sequence verified - the earth contact must make before and break after the power contacts.
8. Mechanical endurance qualified to 100,000 cycles on type-test samples.

ELECTRICAL CHECKS - 100%
9. Wiring verified against the unit schematic; ferrules, terminal tightness and labelling checked.
10. Secondary plug pin-out verified circuit by circuit.
11. Dielectric withstand test at the rated test voltage for one minute, and insulation resistance measured and recorded.
12. Functional test of the feeder logic - starter sequence, protection relay settings, indication and, where fitted, communication.

WHAT YOU RECEIVE
Individual routine test certificate carrying the unit serial number, drawer schedule, wiring diagram, device certificates, and the type-test evidence for the drawer system to support your IEC 61439 verification file.

TRACEABILITY AND SPARES
Every unit is serialised against its drawing revision. When you order a replacement in five years, the drawer that arrives is the drawer that fits. Sample units are supplied for fit-up trials before volume production, and third-party inspection is accepted on request.