SEN Plus MCC Panels – Compliance Review & Technical Clarifications
1- The submitted MCC panel is designed as Form-4 Type 2, and includes two VFDs
(37 kW and 22 kW) mounted vertically in a single cubicle, along with their respective
line reactors and circuit breakers. This configuration raises concerns regarding heat
dissipation and thermal management, especially for the 37 kW VFD.
2- A heat dissipation study is highly recommended to ensure that no thermal derating
will occur due to this compact arrangement. If any derating is identified, it must be
addressed in compliance with Section 2.2-L1 of the project specifications:
Ambient temperature 0 to 50°C. Any required derating shall be
furnished by the contractor/supplier at no extra cost.
3- Although the panel is claimed to be fully type-tested (TTA), the current internal
arrangement (VFDs, reactors, breakers in one cubicle) may not reflect the original
type-tested configuration. Therefore, we request official confirmation and supporting
documentation from ABB and the manufacturer to validate the acceptability of this
layout.
4- Required Submissions
o MCC panel drawings (D/O)
o Valid TTA certificate
o All drawings stamped and approved by ABB
o
5- As per clauses 1.5-QA and 2.2-R, all MCC components including MCCBs,
contactors, overload relays, VFDs, soft starters, motor protection relays, etc., must be
of the same make. The current submission proposes VFDs from Allen-Bradley and
MCCBs from ABB, relays also not the same brand which is not compliant with the
above requirement. Kindly align the component selection accordingly or submit a
formal Technical Query (TQ) for clarification and approval if unification is not
possible.
6- As per clause 2.8-G, "the main incoming breaker/switch must be equipped to
provide (Earth fault protection, Phase failure and phase sequence protection, Trip
functions through a shunt trip coil, the earth fault protection system must also be
time-coordinated with the main incoming breaker of the main distribution board".
The current submission does not include earth fault protection and monitor relay with
the main breaker. This is a deviation from the specifications. Also as per the
specifications, the main breaker of the MCC panel must include earth fault protection,
which shall be time-coordinated with the main incoming breaker of the main
distribution board. In this case, the MCC panel is equipped with an ABB breaker,
while the feeding panel (from Al fanar). Therefore, it is important to verify that the
earth fault protection settings are properly coordinated between both breakers to
ensure correct selectivity and prevent unnecessary tripping of the upstream breaker.
7- As per Specs 2.3-R "Starter Co-Ordination: Motor starter devices shall be of type 2
co-ordination to IEC 60947-4-1. For variable frequency drives, fast acting
semiconducting fuse category gR to IEC 60269-4 or approved equal shall be
provided in case type 2 coordination cannot be achieved" so please we need to
follow the specs and submit the coordination table to check it.
General Notes
1- In light of the above, we kindly request the Manufacturer to review and revise the
shop drawings to ensure compliance with the approved specifications. This will help
prevent any procurement or installation issues later on and confirm that the
manufacturing will proceed in line with project requirements.
2- For any compartment containing control components, panel lights with door-activated
switches shall be installed.
3- A lamp test function shall be provided for all indication lights.
4- We need to verify the CFM rating and the fan selection for the panels to ensure they
are adequate for the required heat dissipation.
5- We need to add a heater and a hygrostat inside the control compartments to prevent
condensation.
