3.2 Insulating the controller
When the main switch (miniature circuit breaker) is in the OFF position, components inside
the cabinets are all isolated from power supply by means of a mechanical switch.
Do not open the cabinet without first disconnecting the main supply cable from the power
line. Remember that even with main switches in OFF positions, there are unguarded terminals
inside the cabinet witch may have dangerous potential across them.
3.3 Insulating by means of SSR: hoe does it work
Remember that solid state relays cannot make a mechanical break of the contacts since they
are semi-conductor devices.
Hence, even if all the regulators are disabled (or in “Manual” mode with output power set to
“0”) only the current on loads will be 0, there may still be some voltage in the heaters.
On the three-phases with neutral supply system, SSR units are always positioned on the live
side of the supply, this keep the residual voltage to a low value. On the three-phases delta
without neutral system supply there always be phase voltage on the heaters when main switch
is in ON position.
Furthermore the SSR may fail in conducting condition. In this case temperature will arise
even if theoretical power is set OFF.
3.4 Specifications and technical characteristics
Table 1: technical characteristics
400 [V] 3 phases with neutral, 240 [V] 3 phases
without neutral
Stable within 10% supply voltage swing
16 A – 3A each zone high – low power zone.
Normal working: zero crossing.
Drying: phase angle fired modulation.
Protection for thermocouple reading
circuits
The 6 TC input on each board are insulated
together (insulating voltage 250V) and towards the
supply (insulation double reinforced).
Sampling time on each channel
According to thermocouples range of measuring
Heater / thermocouples connectors
•
Closed loop (PID), open loop (manual), slave
function.
•
Synchronous heating of all the zones
To Next Page
Loading...