Specifications

NAIROBI OPERATIONAL HUB
UNOPS Building, UN Lane, Off UN Avenue Tel: [phone]
P.O Box 783,Village Market, 00621 E-mail: [e-mail]
Nairobi, Kenya Website: www.unops.org
UNOPS is ISO 9001 certified
Further as a minimum, the following volts-free signals shall be made available:
- Fault
- Overload
- Ramp-up complete
Power circuit
The following features shall be provided as standard:
- Start and stop ramp to be achieved using reduced voltage triggering of
thyristors connected in antiparallel, with each phase individually double-
protected by adequate snubber circuits and varistors to withstand 4kV at
2.5Hz for 60 seconds or more.
- Diode-thyristor paralleling in unacceptable.
- Starter shall be suitable for continuous duty. Further, the circuit must be
suitable for constant mains voltage, even when starter is not in use.
- Electronic overload relay to be provided as option in all ratings above 30A
and as standard feature for heavy-duty applications to protect the unit from
thermal overloads, phase-loss and locked rotor conditions. In addition, an
option of over-current trip (selectable) shall be provided to prevent damage
due to short-circuits.
External electronic or thermal overload relays may be proposed as an option.
- Adequate heat sinking shall be provided. Further, a thyristor overheat trip
shall be provided for added protection.
- Adequately sized terminals shall be provided for linking to cables. Where
busbars are used, terminal expansion attachments shall be provided
accordingly.
Technical Support
The equipment shall be supplied complete with comprehensive documentation
comprising the installation and operation instructions. In addition, the following
documentation shall be provided on request and where applicable:
- Selection details including starting curves based on manufacturer’s
recommendations.
- Coordination tables (where used) for Type-2 coordination as per IEC.
- Connection drawings for the scheme used.