VFD Control Panels for a Parcel Conveyor System
Sector:
Materials Handling & Conveying
Type:
New Build - Control System
Platform:
Siemens
Certification:
CE / UKCA
Summary
DelaControl designed, built, and tested a main control panel and two VFD motor control boxes to provide variable-speed forward/reverse drive control and DOL bypass capability for a parcel conveyor system, delivering a complete panel package ready for site installation.
Challenge
A conveyor system operator required a new control system to manage two 3.0 kW conveyor motors, each needing variable-frequency drive control with forward and reverse capability as well as a direct-on-line bypass mode.
The system required a main control panel with per-motor start/stop controls, MPCB trip indication, overall power monitoring, and an AM/PM selector switch, all built to a proven design standard previously established on an earlier system for the same operator.
Solution
DelaControl designed and built a main control panel and two dedicated VFD motor control boxes — one per motor — built in Rittal enclosures using Siemens SINAMICS G120 drives (CU240E-2 PN-F control unit paired with PM240-2 power module). Each VFD box houses its own bypass/forward-reverse selector switches and a reversing contactor arrangement, giving operators the choice of VFD or DOL starter operation at the local box. Status of the bypass switch is indicated on the main panel.
The main panel was equipped with a Siemens SENTRON PAC3220 power monitor, Siemens SITOP redundant 24 V dc power supplies, a Pilz PNOZ safety relay for emergency stop monitoring (rated PLc), and a comprehensive suite of Siemens MCBs, interface relays, and Weidmuller terminal blocks throughout. Rittal Therm thermal calculations were carried out to verify enclosure cooling requirements.
The full documentation package included AutoCAD LT general arrangement drawings, EPlan electrical schematics, a Declaration of Conformity to the Low Voltage and EMC Directives (BS EN 60204, BS EN 61439-1/-2), thermal calculations, and a Factory Acceptance Test schedule and signed certificate. Pre-delivery testing used IO simulation test boxes and test motors to verify correct system operation before dispatch.
Key Facts
• Two 3.0 kW motors controlled — each with its own dedicated 600 mm × 600 mm VFD control box
• Siemens SINAMICS G120 drives (CU240E-2 PN-F control unit + PM240-2 power module) with PROFINET interface and Safety Integrated STO
• Each motor capable of VFD or DOL bypass operation, with forward/reverse selection at the local VFD box
• Main control panel housed in a Rittal 800 × 1000 × 300 mm enclosure
• Siemens SENTRON PAC3220 power monitor (Modbus TCP) fitted to main panel
• Redundant Siemens SITOP 24 V dc power supplies with selectivity and redundancy modules
• Pilz PNOZ X2 safety relay for emergency stop function, rated PLc
• 29 Siemens interface relays and 7 analogue timer relays fitted in main panel
• ABB 80 A 4-pole isolator as main panel incomer
• Mersen 80 A fused switch protection on incoming supply
• Full documentation pack: EPlan schematics, AutoCAD GA drawings, FAT schedule/certificate, thermal calculations, Declaration of Conformity