5 | electrical connection – GEA Bock HG4 User Manual
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5| Electrical connection
ATTENTION! 
Terminals 1 - 6 on the trigger 
unit MP 10 and terminals PTC 
1 and PTC 2 on the compres-
sor terminal board must not 
come into contact with mains 
voltage. This would destroy the 
trigger unit and PTC sensors.
The supply voltage at L1-N 
(+/- for DC 24 V version) must 
be identical to the voltage at 
terminals	11,	12,	14	and	43.	
5.6 Electronic trigger unit MP 10
The	 compressor	 motor	 is	 fitted	 with	 cold	 conductor	 temperature	 sensors	 (PTC)	 connected	 to	 the	
electronic trigger unit MP 10 in the terminal box. Readiness to operate is signalled by the H3 LED 
(green) after the power supply is applied. In the case of excess temperature in the motor winding, the 
unit switches off the compressor and the H1 LED lights red.
The hot gas side of the compressor can also be protected against overtemperature using a thermal 
protection thermostat (accessory). The H2 LED (red) is provided for the protection function.
The unit trips when an overload or inadmissible operating conditions occur. Find and remedy 
the cause.
5.7 Connection of the trigger unit MP10
INFO!
Connect the trigger unit MP10 in accordance with the circuit dia-
gram. Protect the trigger unit with a delayed-action fuse (F) of max. 
4	A.	In	order	to	guarantee	the	protection	function,	install	the	trigger	
unit	as	the	first	element	in	the	control	power	circuit.
Temperature monitoring connections:
Motor winding:
Terminals 1 - 2
Thermal protection thermostat:
Terminals 3 - 4
Restart prevention:
Terminals 5 - 6
INFO!
The	unit	has	a	restart	prevention	device.	After	you	have	rectified	the	
fault,	either	interrupt	the	mains	voltage.	This	unlocks	the	restart	pre-
vention device and the LEDs H1 and H2 go out.
Terminal board
Fig. 21
