(Page 2)
Larger, more powerful shakers give off more heat. Cooling of the shaker becomes essential, particularly for extended operation at high-force levels. Sentek Dynamics’ shakers providing less than 65 kN (14,300 lb) of force are air-cooled by a remote blower. Room-temperature air is drawn into the shaker through a shroud surrounding the load table. This air passes through the magnetic gap, cooling the voice coil and the field coils as well as extracting heat from the iron structure. The air is drawn to a plenum chamber at the bottom of the shaker and out through a flexible duct to the blower. The blower may be mounted outside of the workspace to minimize noise and re-circulated heat. An interlock prevents shaker operation if the blower is not drawing sufficient air through the shaker.
The H, P and E Series shakers are our most powerful offerings, providing peak force ratings from 65 kN (14,300 lb) to 400 kN (88,000 lb). These large shakers are all water-cooled. The armature is wrapped with a flat cooling tube and the body cylinder has cast-in water passages. Each system is provided with a cooling unit which passes the heat generated within the shaker into a flow of outside water. Each cooling unit is sized to match the shaker and incorporates two heat exchangers, two pumps and a single divided tank for distilled water. Two internal closed-loop cooling circuits provide distilled water to the armature and to the field coils. One heat exchanger and pump supplies water to the armature circuit; the other heat exchanger and pump supplies water to the field circuit. An outer circuit passes the extracted heat from the inner circuits to a facility raw water source, typically from a remotely located chiller. Water pressure in the armature and field circuits is monitored by sensors as is the facility raw water pressure. If any values surpass their respective settings, the system alarm will sound and the amplifier will shut-off.
A typical low-force air-cooled shaker system.