VEAB VFL-M, Инструкция по установке

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5
VFLPG/VFL/VTL - M / ML
Overheating
If overheating cut-outs with manual reset has been activated, the
following should be observed:
1. Only authorized electricians are allowed to remove the lid.
2. The mains supply voltage must be switched off.
3. Investigate carefully the reason for activation of the cut-out.
4. When the fault has been eliminated, the cut-out can be reset.
Connection examples
• Duct heaters may have an arbitrary number of load steps.
Look at the wiring diagram/documentation on the inside
of the lid of the topical heater. The heating elements of each
load step may be interconnected in several different ways.
Look at the load step #1 in the example A on page 16 to see
some variants of the possible interconnections (further va-
riants may occur). Load steps that has lower loading may be
single or dual phase, as shown in the example B for load steps
#1 and #2. The load steps are normally designed for either
sequential or binary control, as shown in the examples G, H
and I on page 17. Other customized load step divisions may
occur.
• The duct heater is equipped with thermal protection (over -
heat cut-outs). The heater design, the scope of use, the
maximum allowed outgoing air temperature, etc. affects
the nature of the duct heater thermal protection. Heaters
with maximum allowed outgoing air temperature of 50°C,
normally has at least one thermal protection with manual
reset (set at 120°C) and at least one thermal protection with
automatic reset (set at 75°C). The number of thermal protec-
tion varies, due to the duct size of the heater, as shown in the
examples A and C on page 16.
• Heaters designed for higher outgoing air temperatures, are
normally equipped with manual reset thermal protections
only as shown in the example D. Other customized designs
may occur.
• Heaters may be equipped with thermal protection that has
change-over contacts, alternatively a relay may be involved in
the circuitry. Look at the examples D, E and F. The change-
over contacts, or the relay contacts, may be used for indica-
tion of tripped thermal protection. The relay contacts must
not be used for interlocking purposes, only for indication or
alarm.
• The heater thermal protections must be part of the external
control circuitry, as shown in the examples J, K, L and M.
• The examples shown in this document are representative and
common variants but other variants may occur. Look at the
wiring diagram/documentation on the inside of the lid of the
topical heater.
Troubleshooting
Full heating power but no regulation
• The fault is not in the duct heater. Check the external con -
trol/thermostat.
No heating
• Check whether or not there is mains voltage at the heater
terminal blocks. If there is no voltage at the terminals, then
the fault is not in the heater. Check the external control/
thermostat, fuses, switches, etc.
• If there is mains voltage at the terminals, then check whether
the thermal protection (the overheating cut-outs) or the
heating elements are open circuit. If thermal protection with
manual reset has tripped, then the fault must be investigated
and eliminated before the reset action. See ”Overheating”.