6 | electrical connection – GEA Bock HGZ7 User Manual
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6| Electrical connection
Terminal box
Fig. 30
6.5 Connection of the trigger unit MP10
Temperature monitoring connections:
Motor winding:
Terminals 1 - 2
Thermal protection thermostat:
Terminals 3 - 4
Restart prevention:
Terminals 5 - 6
ATTENTION 
Terminals 1 - 6 on the trigger 
unit MP 10 and terminals PTC 
1 and PTC 2 on the compressor 
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. 
INFO
The	unit	has	a	restart	prevention	device.	After	you	have	rectified	the
fault, interrupt the mains voltage. This unlocks the restart prevention
device and the LEDs H1 and H2 go out.
INFO
Connect the trigger unit MP10 in accordance with the circuit 
diagram. 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.
6.4 Electronic trigger unit MP10
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.
