How to wire to control heating box & blower system ?

How to wire to control heating box & blower system ?

seven (7) heaters , 3 phase supply , Digital temperature controller of P + D type , K type thermocouple for heat sensing , a Off delay timer of 0.1 sec to 30 sec , a 3 phase contactor of 220 V coil , digital temperature controller of 220 V ac supply .....

From 3 phases , each single phase goes to 2 heaters each (pair of 2 heaters) & the third phase goes to the 3 pair heater (pair of 3 heaters) , the neutral is common to every heater ........

the output of the Digital temperature controller , one of them goes to the off delay timer & one goes to the coil of the 3 phase contactor . I couldn't understand this

thanks

Kindly tell me how to reconnect these things together to complete the task of controlling the heater & blower system , blower also 3 phase

The controller switches the fans on and off or controls their speed to stabilise some temperature. BUT when you turn the system off, you need to let the fan run for 10 mins or so to cool the heaters down, else they or something else might get damaged. this is commonly called a "cooling over run".
Frank

The thermocouple must be to detect that fire has successfully ignited inside the furnace/boiler. The thermocouple is installed so it is in the flame, or near it.

(My furnace has no pilot flame, so it does not have a separate thermocouple to detect that pilot flame is lit.)

If fire is not detected even though thermostat is calling for heat, then no further steps should occur. You should test for this condition when installation is complete. It is a vital safeguard.

One of your items should be a board that governs all actions. The thermocouple must plug in somewhere, where its signal can be amplified.

The relay coil also plugs into the board. Also the timer.

I had a new furnace installed. The serviceman told me that fire needs to be detected for several seconds, before the blower will turn on. There should be a circuit on the controller board, which delays sending current to the relay for 10 to 20 seconds.

The separate timer which you mentioned is probably for the purpose to keep the blowers running for a while after the furnace shuts off (as post #2 states).

This is only partial information. You'll need to get more information than my post has.