A drawing is the most useful thing an equipment buyer can send. An enquiry that matches the drawing line by line needs fewer rounds of questions before an offer can be prepared. The list below is the set of parameters that usually decides whether an assembly can be quoted from a single-line diagram and a layout, and which items still need to be confirmed.
1. Single-line and layout documents
- Single-line diagram and cabinet schedule
- Plan or layout drawing with cubicle dimensions and arrangement
- Secondary control schematics, terminal schedules and cable schedules
- I/O list, interlock logic and control voltage where a PLC or control system is involved
2. Ratings
| Parameter | What to state |
|---|---|
| Rated operational voltage Ue | Value and phase arrangement |
| Rated insulation voltage Ui | Value |
| Frequency | 50 Hz / 60 Hz |
| Main busbar rated current | Value in amperes |
| Distribution busbar rated current | Value in amperes, where applicable |
| Rated short-time withstand current Icw | Value in kA and the duration |
| Degree of protection | IP code |
| Form of separation and earthing arrangement | As required by the project |
Reference ranges for the low-voltage assemblies documented on this site: main busbar 400–4000 A, Icw 30 kA and 80 kA depending on the cabinet type, Ue 230/380/400 V, Ui 690 V, IP30–IP65. The values applying to a particular configuration are the ones on its sample page in the type-test report. Configurations outside the documented range are handled as built to drawing.
3. Construction and environment
- Fixed or withdrawable construction; indoor or outdoor installation
- Number of cubicles, dimensions, surface colour and door arrangement
- Cable entry from top or bottom, busbar material and cross-section
- Ambient temperature, altitude, dust, moisture and wash-down conditions
4. Components and protection
- Preferred component brands and any approved alternatives
- Breaker frame sizes and ratings, protection functions and settings
- Meters, relays, CT and PT ratios, control transformers
- Interlocks, indication, communication interface and spare capacity
5. Documentation and verification
- Standard family, part and edition year required by the project
- Which design-verification items are expected, and which document covers each
- Type-test report pages, routine test records and drawings for approval
- Manuals, nameplates, labels and packing list
6. Commercial and delivery
- Quantity, destination and delivery terms
- Required delivery date, packing, spare parts and warranty documentation
A short enquiry template
Subject: Enquiry — LV distribution assembly, [project name]
Attached: single-line diagram, layout, cabinet schedule, control schematics.
Ratings: Ue ___ V / Ui ___ V / ___ Hz; main busbar ___ A; Icw ___ kA / ___ s; IP___.
Construction: ___ cubicles, fixed / withdrawable, indoor / outdoor, dimensions ___.
Components: [preferred brands and breaker ratings].
Environment: [dust / moisture / wash-down / ambient temperature / altitude].
Documentation: [standard and edition, verification items, report pages, routine tests].
Delivery: quantity ___, destination ___, required date ___.
Please confirm which items are covered by the type-test report for the proposed configuration, and which are built to drawing.
Related reading: how to read a type-test report and GB/T 7251 and IEC 61439.
Equipment specifications and project enquiries are handled at tonxel.com.